Optical transmission apparatus, optical reception apparatus, optical communication apparatus, optical communication system, and methods of controlling them

ABSTRACT

An optical transmission apparatus (1_1) according to the present invention includes a first transmission unit (11_1) that transmits a first optical transmission signal (21_1), a second transmission unit (11_2) that transmits a second optical transmission signal (21_2), and an output unit that outputs, when the first optical transmission signal (21_1) and the second optical transmission signal (21_2) share a set of information, both the first optical transmission signal (21_1) and the second optical transmission signal (21_2) to a first path (26_1) and outputs, when the first optical transmission signal (21_1) and the second optical transmission signal (21_2) do not share the set of information, one of the first optical transmission signal (21_1) and the second optical transmission signal (21_2) to a second path (26_2).

TECHNICAL FIELD

The present invention relates to an optical transmission apparatus, anoptical reception apparatus, an optical communication apparatus, anoptical communication system, and methods of controlling them.

BACKGROUND ART

With an explosive increase in demand of a broadband multimediacommunication service such as the Internet or video distribution, adense wavelength-division multiplexing optical fiber communicationsystem, which is suitable for a long-distance and large-capacitytransmission and is highly reliable, has been introduced in trunk linenetworks and metropolitan area networks. In subscriber systems, anoptical fiber access service spreads rapidly. In such an optical fibercommunication system, cost reduction for laying optical fibers asoptical transmission lines and improvement of spectral efficiency peroptical fiber are important. Therefore, a wavelength division multiplex(WDM), which multiplexes multiple optical signals having differentwavelengths, is widely used. In the WDM technology, one wavelength isused for one channel. On the other hand, in recent years, a SuperChanneltechnology, which can achieve a transmission capacity that exceeds 100Gbps for each bandwidth of one channel of the WDM, has been focused. Inthis SuperChannel technology, a plurality of wavelengths (sub-carriers)are used for the bandwidth of one channel, whereby it is possible tomultiplex wavelengths with high density. Therefore, when thetransmission capacity increases to 400 Gbps or 1 Tbps in the future,this SuperChannel technology will become more important.

Patent Literature 1 and 2 disclose techniques related to an opticalcommunication using the WDM. Patent Literature 1 discloses a techniquerelated to an optical network apparatus capable of performing anefficient operation, management, and maintenance of a network. PatentLiterature 2 discloses a technique related to an optical transmissionapparatus capable of reducing an influence of intermixing noise when anelectric signal including a plurality of sub-carriers is transmitted byanalog optical modulation.

CITATION LIST Patent Literature

[Patent Literature 1] Japanese Unexamined Patent Application PublicationNo. 2003-008513

[Patent Literature 2] Japanese Unexamined Patent Application PublicationNo. 2008-206063

SUMMARY OF INVENTION Technical Problem

In the communication network, there is a fluctuation in an amount oftraffic between predetermined nodes. Therefore, it is not necessary thatthe transmission between predetermined nodes be always performed at amaximum transmission capacity. On the other hand, as described inBackground Art, in the optical communication using the WDM technology,one wavelength is used for one channel. Therefore, in the opticalcommunication apparatus using the WDM technology, there are only twooptions: whether to turn off the communication or to perform thecommunication at the maximum transmission capacity, and it is impossibleto set the transmission capacity to an intermediate value.

On the other hand, when the SuperChannel technology is used, a pluralityof wavelengths are used in the bandwidth of one channel of the WDM,whereby it is possible to set the transmission capacity to theintermediate value. Based on this point, the present inventors havefound that, when the transmission capacity is set to an intermediatevalue using a part of the plurality of wavelengths in the bandwidth ofone channel for one transmission apparatus, the resources can beallocated to the other transmission apparatuses using the remainingwavelengths.

In view of the above description, one exemplary object of the presentinvention is to provide an optical transmission apparatus, an opticalreception apparatus, an optical communication apparatus, an opticalcommunication system, and methods of controlling them capable ofefficiently allocating resources in an optical communication network.

Solution to Problem

An optical transmission apparatus according to the present inventionincludes: a first transmission unit that transmits a first opticaltransmission signal; a second transmission unit that transmits a secondoptical transmission signal; and an output unit that outputs, when thefirst optical transmission signal and the second optical transmissionsignal share a set of information, both the first optical transmissionsignal and the second optical transmission signal to a first path andoutputs, when the first optical transmission signal and the secondoptical transmission signal do not share the set of information, one ofthe first optical transmission signal and the second opticaltransmission signal to a second path.

An optical reception apparatus according to the present inventionincludes: first and second reception units that receive a sub-carrierreception signal; and a switch unit that outputs a first sub-carrierreception signal and a second sub-carrier reception signal that havebeen input to the first and second reception units, in which: when thefirst and second sub-carrier reception signals share a set ofinformation, the switch unit receives the first and second sub-carrierreception signals via one path and outputs the first sub-carrierreception signal to the first reception unit and the second sub-carrierreception signal to the second reception unit, and when the firstsub-carrier reception signal and the second sub-carrier reception signaldo not share the set of information, the switch unit receives the firstand second sub-carrier reception signals via paths different from eachother and outputs the first sub-carrier reception signal to the firstreception unit and the second sub-carrier reception signal to the secondreception unit.

An optical communication apparatus according to the present inventionincludes: a first transmission unit that transmits a first opticaltransmission signal; a second transmission unit that transmits a secondoptical transmission signal; an output unit that outputs, when the firstoptical transmission signal and the second optical transmission signalshare a set of information, both the first optical transmission signaland the second optical transmission signal to a first path and outputs,when the first optical transmission signal and the second opticaltransmission signal do not share the set of information, one of thefirst optical transmission signal and the second optical transmissionsignal to a second path; first and second reception units that receive asub-carrier reception signal; and a switch unit that outputs a firstsub-carrier reception signal and a second sub-carrier reception signalthat have been input to the first and second reception units, in which:the switch unit receives, when the first and second sub-carrierreception signals share a set of information, the first and secondsub-carrier reception signals via one path and outputs the firstsub-carrier reception signal to the first reception unit and the secondsub-carrier reception signal to the second reception unit, and theswitch unit receives, when the first sub-carrier reception signal andthe second sub-carrier reception signal do not share the set ofinformation, the first and second sub-carrier reception signals viapaths different from each other and outputs the first sub-carrierreception signal to the first reception unit and the second sub-carrierreception signal to the second reception unit.

An optical communication system according to the present inventionincludes an optical transmission apparatus and first and second opticalreception apparatuses, in which: the optical transmission apparatusincludes: a first transmission unit that transmits a first opticaltransmission signal; a second transmission unit that transmits a secondoptical transmission signal; and an output unit that outputs, when thefirst optical transmission signal and the second optical transmissionsignal share a set of information, both the first optical transmissionsignal and the second optical transmission signal to the first opticalreception apparatus and outputs, when the first optical transmissionsignal and the second optical transmission signal do not share the setof information, one of the first optical transmission signal and thesecond optical transmission signal to the second optical receptionapparatus.

An optical communication system according to the present inventionincludes: an optical transmission apparatus that transmits first andsecond optical transmission signals; first and second optical receptionapparatuses that receive the first and second optical transmissionsignals; and a controller that controls the optical transmissionapparatus, in which the optical transmission apparatus outputs the firstoptical transmission signal and a second optical transmission signalthat shares a set of information with the first optical transmissionsignal to the first optical reception apparatus according to aninstruction from the controller and outputs a second opticaltransmission signal that does not share the set of information with thefirst optical transmission signal to the second optical receptionapparatus.

An optical communication system according to the present inventionincludes first and second optical transmission apparatuses and anoptical reception apparatus, in which: the optical reception apparatusincludes: first and second reception units that receive a sub-carrierreception signal; and a switch unit that outputs a first sub-carrierreception signal and a second sub-carrier reception signal that havebeen input to the first and second reception units, when the first andsecond sub-carrier reception signals share a set of information, theswitch unit receives the first and second sub-carrier reception signalsfrom one optical transmission apparatus and outputs the firstsub-carrier reception signal to the first reception unit and the secondsub-carrier reception signal to the second reception unit, and when thefirst sub-carrier reception signal and the second sub-carrier receptionsignal do not share the set of information, the switch unit receives thefirst and second sub-carrier reception signals via paths different fromeach other and outputs the first sub-carrier reception signal to thefirst reception unit and the second sub-carrier reception signal to thesecond reception unit.

A controller according to the present invention causes, in an opticalcommunication system including an optical transmission apparatus andfirst and second optical reception apparatuses, the optical transmissionapparatus to output a first optical transmission signal and a secondoptical transmission signal that share a set of information with thefirst optical transmission signal to the first optical receptionapparatus and to output a second optical transmission signal that doesnot share the set of information with the first optical transmissionsignal to the second optical reception apparatus.

A method of controlling an optical communication system according to thepresent invention is method of controlling an optical communicationsystem including an optical transmission apparatus and first and secondoptical reception apparatuses, in which: the optical transmissionapparatus includes: a first transmission unit that transmits a firstoptical transmission signal; a second transmission unit that transmits asecond optical transmission signal; and an output unit that outputs,when the first optical transmission signal and the second opticaltransmission signal share a set of information, both the first opticaltransmission signal and the second optical transmission signal to thefirst optical reception apparatus, and when the first opticaltransmission signal and the second optical transmission signal do notshare the set of information, outputs one of the first opticaltransmission signal and the second optical transmission signal to thesecond optical reception apparatus, and each of the optical transmissionapparatus and the first and second optical reception apparatuses iscontrolled according to a state of communication of the opticalcommunication system.

A program according to the present invention is a program forcontrolling an optical communication system including an opticaltransmission apparatus and first and second optical receptionapparatuses, in which: the optical transmission apparatus includes: afirst transmission unit that transmits a first optical transmissionsignal; a second transmission unit that transmits a second opticaltransmission signal; and an output unit that outputs, when the firstoptical transmission signal and the second optical transmission signalshare a set of information, both the first optical transmission signaland the second optical transmission signal to the first opticalreception apparatus, and outputs, when the first optical transmissionsignal and the second optical transmission signal do not share the setof information, one of the first optical transmission signal and thesecond optical transmission signal to the second optical receptionapparatus, and the program causes a computer to execute processing forcontrolling each of the optical transmission apparatus and the first andsecond optical reception apparatuses according to a state ofcommunication of the optical communication system.

An optical transmission method according to the present inventionincludes: generating a first optical transmission signal; generating asecond optical transmission signal; and outputting, when the firstoptical transmission signal and the second optical transmission signalshare a set of information, both the first optical transmission signaland the second optical transmission signal to a first path andoutputting, when the first optical transmission signal and the secondoptical transmission signal do not share the set of information, one ofthe first optical transmission signal and the second opticaltransmission signal to a second path.

An optical reception method according to the present invention receives,when first and second sub-carrier reception signals share a set ofinformation, the first and second sub-carrier reception signals via onepath and outputs the first sub-carrier reception signal to a firstreception unit and the second sub-carrier reception signal to a secondreception unit and receives, when the first sub-carrier reception signaland the second sub-carrier reception signal do not share the set ofinformation, the first and second sub-carrier reception signals viapaths different from each other, outputs the first sub-carrier receptionsignal to the first reception unit, and outputs the second sub-carrierreception signal to the second reception unit.

Advantageous Effects of Invention

According to the present invention, it is possible to provide an opticaltransmission apparatus, an optical reception apparatus, an opticalcommunication apparatus, an optical communication system, and methods ofcontrolling them capable of efficiently allocating resources in anoptical communication network.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an optical transmission apparatusaccording to a first exemplary embodiment;

FIG. 2 is a diagram showing an optical communication system according toa comparative example;

FIG. 3 is a diagram showing the optical communication system accordingto the comparative example;

FIG. 4 is a diagram for describing effects of the present invention;

FIG. 5 is a block diagram showing an optical transmission apparatusaccording to a second exemplary embodiment;

FIG. 6 is a diagram for describing an arrangement of sub-carriers;

FIG. 7 is a diagram for describing an arrangement of sub-carriers;

FIG. 8 is a block diagram showing an optical transmission apparatusaccording to a third exemplary embodiment;

FIG. 9 is a diagram showing one example of the sub-carriers (WDM);

FIG. 10 is a diagram showing another example of the sub-carriers (OFDMmodulation);

FIG. 11 is a block diagram showing an optical transmission apparatusaccording to a fourth exemplary embodiment;

FIG. 12 is a block diagram showing the optical transmission apparatusaccording to the fourth exemplary embodiment;

FIG. 13 is a block diagram showing the optical transmission apparatusaccording to the fourth exemplary embodiment;

FIG. 14 is a block diagram showing an optical reception apparatusaccording to a fifth exemplary embodiment;

FIG. 15 is a block diagram showing an optical reception apparatusaccording to a sixth exemplary embodiment;

FIG. 16 is a block diagram showing an optical reception apparatusaccording to a seventh exemplary embodiment;

FIG. 17 is a block diagram showing an optical reception apparatusaccording to an eighth exemplary embodiment;

FIG. 18 is a block diagram showing the optical reception apparatusaccording to the eighth exemplary embodiment;

FIG. 19 is a block diagram showing the optical reception apparatusaccording to the eighth exemplary embodiment;

FIG. 20 is a block diagram showing an optical communication apparatusaccording to a ninth exemplary embodiment;

FIG. 21 is a block diagram showing an optical communication systemaccording to a tenth exemplary embodiment;

FIG. 22 is a block diagram showing an optical communication systemaccording to an eleventh exemplary embodiment;

FIG. 23 is a block diagram showing a controller included in the opticalcommunication system according to the eleventh exemplary embodiment;

FIG. 24 is a block diagram showing a controller included in an opticalcommunication system according to a twelfth exemplary embodiment;

FIG. 25 is a block diagram showing an optical communication systemaccording to a thirteenth exemplary embodiment;

FIG. 26 is a block diagram showing an optical communication systemaccording to a fourteenth exemplary embodiment; and

FIG. 27 is a block diagram showing an optical communication systemaccording to a fifteenth exemplary embodiment.

DESCRIPTION OF EMBODIMENTS First Exemplary Embodiment

In the following description, with reference to the drawings, exemplaryembodiments of the present invention will be described. FIG. 1 is ablock diagram showing an optical transmission apparatus 1_1 according toa first exemplary embodiment. As shown in FIG. 1, the opticaltransmission apparatus 1_1 according to this exemplary embodimentincludes a first transmission unit 11_1, a second transmission unit11_2, and an output unit 12. In the following description, the first andsecond transmission units may be referred to as sub-carrier transmissionunits.

The first transmission unit 11_1 transmits a first optical transmissionsignal 21_1. The second transmission unit 11_2 transmits a secondoptical transmission signal 21_2. That is, transmission data is suppliedto each of the first transmission unit 11_1 and the second transmissionunit 11_2 and the first transmission unit 11_1 and the secondtransmission unit 11_2 respectively generate the first opticaltransmission signal 21_1 and the second optical transmission signal 21_2to transmit the transmission data. The first optical transmission signal21_1 and the second optical transmission signal 21_2 are signals totransmit the transmission data using sub-carriers.

The optical transmission apparatus 1_1 according to this exemplaryembodiment uses a WDM technology, which multiplexes a plurality ofoptical signals having different wavelengths and transmits themultiplexed signal. That is, the first optical transmission signal 21_1and the second optical transmission signal 21_2 respectively generatedin the first transmission unit 11_1 and the second transmission unit11_2 have wavelengths different from each other. In the opticaltransmission apparatus according to this exemplary embodiment, inparticular, a SuperChannel technology, which allocates a plurality ofwavelengths (sub-carriers) to the bandwidth of one channel of the WDM,can be used. By using this SuperChannel technology, it is possible tomultiplex wavelengths with high density and to increase the transmissioncapacity.

When the first optical transmission signal 21_1 and the second opticaltransmission signal 21_2 share a set of information, the output unit 12outputs both the first optical transmission signal 21_1 and the secondoptical transmission signal 21_2 to one path (e.g., a first path 26_1).

On the other hand, when the first optical transmission signal 21_1 andthe second optical transmission signal 21_2 do not share the set ofinformation, the output unit 12 outputs one of the first opticaltransmission signal 21_1 and the second optical transmission signal 21_2to a second path. For example, when the first optical transmissionsignal 21_1 and the second optical transmission signal 21_2 do not sharethe set of information, the output unit 12 may output the first opticaltransmission signal 21_1 to the first path 26_1 and the second opticaltransmission signal 21_2 to a second path 26_2. Alternatively, forexample, when the first optical transmission signal 21_1 and the secondoptical transmission signal 21_2 do not share the set of information,the output unit 12 may output the first optical transmission signal 21_1to the second path 26_2 and the second optical transmission signal 21_2to the first path 26_1. In other words, when the first opticaltransmission signal 21_1 and the second optical transmission signal 21_2do not share the set of information, the output unit 12 outputs thefirst optical transmission signal 21_1 and the second opticaltransmission signal 21_2 to paths different from each other.

The case in which the first optical transmission signal 21_1 and thesecond optical transmission signal 21_2 share the set of informationincludes, for example, a case in which the first transmission unit 11_1and the second transmission unit 11_2 transmit desired transmission datain parallel using the first optical transmission signal 21_1 and thesecond optical transmission signal 21_2.

On the other hand, the case in which the first optical transmissionsignal 21_1 and the second optical transmission signal 21_2 do not sharethe set of information includes, for example, a case in which the firsttransmission unit 11_1 and the second transmission unit 11_2independently transmit desired transmission data using the first opticaltransmission signal 21_1 and the second optical transmission signal 21_2(i.e., a case in which the first transmission unit 11_1 transmits apredetermined first transmission data using the first opticaltransmission signal 21_1 and the second transmission unit 11_1 transmitsa predetermined second transmission data using the second opticaltransmission signal 21_1). In this case, since the first opticaltransmission signal 21_1 and the second optical transmission signal 21_2include respective pieces of transmission data independent from eachother, the first optical transmission signal 21_1 and the second opticaltransmission signal 21_2 can be output to the paths different from eachother (the first path 26_1 and the second path 26_2).

The first path 26_1 is a path connected to a first optical receptionapparatus (not shown) and the second path 26_2 is a path connected to asecond optical reception apparatus (not shown).

As described above, in the optical transmission apparatus 1_1 accordingto this exemplary embodiment, the output destinations of the firstoptical transmission signal 21_1 and the second optical transmissionsignal 21_2 are switched using the output unit 12. It is thereforepossible to provide the optical transmission apparatus capable ofefficiently allocating the resources. The reason therefore will bedescribed later in detail.

FIGS. 2 and 3 are diagrams showing an optical communication systemaccording to a comparative example and show one example of the opticalcommunication system using the SuperChannel technology. The opticalcommunication system shown in FIGS. 2 and 3 includes opticalcommunication apparatuses 101_a to 101_c. The optical communicationapparatus 101_a includes a plurality of transceiver units 102_a and asingle transmission/reception port 103_a. The plurality of transceiverunits 102_a are configured to be able to transmit and receive data usingwavelengths (sub-carriers) different from each other. That is, theoptical communication apparatus 101_a is able to allocate a plurality ofwavelengths (sub-carriers) to the bandwidth of one channel of the WDM.The respective transceiver units 102_a are configured to be able totransmit and receive data using the respective sub-carriers. The same isapplicable to the optical communication apparatus 101_b and the opticalcommunication apparatus 101_c.

In the optical communication system shown in FIGS. 2 and 3, the opticalcommunication apparatus 101_a and the optical communication apparatus101_b can be connected each other via an optical fiber 105, the opticalcommunication apparatus 101_a and the optical communication apparatus101_c can be connected each other via an optical fiber 106, and theoptical communication apparatus 101_b and the optical communicationapparatus 101_c can be connected each other via an optical fiber 107.

The example shown in FIG. 2 shows the case in which the opticalcommunication apparatus 101_a and the optical communication apparatus101_b are connected via the optical fiber 105 and the opticalcommunication apparatus 101_a and the optical communication apparatus101_b communicate with each other at a maximum transmission capacity(100%).

In the communication network, there is a fluctuation in an amount oftraffic between predetermined nodes. Therefore, it is not necessary thatthe transmission between the optical communication apparatus 101_a andthe optical communication apparatus 101_b be always performed at themaximum transmission capacity. As described in Background Art, in theoptical communication using the WDM technology, one wavelength is usedfor one channel. Therefore, in the optical communication apparatus usingthe WDM technology, there are only two options: whether to turn off thecommunication or to perform the communication at the maximumtransmission capacity, and it is impossible to set the transmissioncapacity to an intermediate value.

On the other hand, when the SuperChannel technology is used, a pluralityof wavelengths are used in the bandwidth of one channel of the WDM,whereby it is possible to set the transmission capacity to theintermediate value. Therefore, as shown in FIG. 3, for example, thetransmission capacity between the optical communication apparatus 101_aand the optical communication apparatus 101_b can be set to 50% of themaximum transmission capacity. In this case, however, some of thetransceiver units 102_a of the optical communication apparatus 101_awhich are denoted by transceiver units 108_a are not to be used.Further, some of the transceiver units 102_b of the opticalcommunication apparatus 101_b which are denoted by transceiver units108_b are not to be used.

When the SuperChannel technology is used, the signals transmitted orreceived by the respective transceiver units 102_a share the set ofinformation. In other words, the respective transceiver units 102_atransmit or receive data in parallel. Therefore, the opticalcommunication apparatus 101_a is configured to transmit or receiveoptical signals via the single port 103_a. Therefore, even when thereare transceiver units 108_a, which are not to be used, among thetransceiver units 102_a of the optical communication apparatus 101_a, itis impossible to use the transceiver units 108_a that are not to be usedfor the communication with another optical communication apparatus 101_cand the resources are wasted.

FIG. 4 is a diagram for describing effects of the present invention.While the effects of the present invention are described in FIG. 4 usingan optical communication apparatus (an optical communication apparatusthat can transmit and receive data), the effects of the presentinvention may also be obtained in a similar way in the opticaltransmission apparatus and the optical reception apparatus as well.

The optical communication system shown in FIG. 4 includes opticalcommunication apparatuses 110_a to 110_c. The optical communicationapparatus 110_a includes a plurality of transceiver units 111_a, aswitch unit 112_a, and a plurality of transmission/reception ports 113_1a and 113_2 a. The plurality of transceiver units 111_a are configuredto be able to transmit and receive data using sub-carriers differentfrom one another. That is, the optical communication apparatus 110_a isable to allocate the plurality of wavelengths (sub-carriers) to thebandwidth of one channel of the WDM. The same is applicable to theoptical communication apparatus 110_b and the optical communicationapparatus 110_c.

As described above, the optical communication apparatus 110_a includesthe plurality of transmission/reception ports 113_1 a and 113_2 a and isable to switch the transceiver units 111_a connected to the plurality oftransmission/reception ports 113_1 a and 113_2 a using the switch unit112_a. Accordingly, even when there are unused transceiver units in theplurality of transceiver units 111_a of the optical communicationapparatus 110_a, the unused transceiver units can be allocated to thecommunication with another optical communication apparatus.

For example, in the optical communication system shown in FIG. 3, whenthe transmission capacity between the optical communication apparatus101_a and the optical communication apparatus 101_b is set to 50% of themaximum transmission capacity, there are unused transceiver units 108_aof the transceiver units 102_a of the optical communication apparatus101_a and the resources are wasted. On the other hand, in the opticalcommunication system shown in FIG. 4, the unused transceiver units(corresponding to the transceiver units 108_a shown in FIG. 3) of theoptical communication apparatus 111_a are connected to thetransmission/reception port 113_2 a using the switch unit 112_a, wherebyit is possible to allocate the unused transceiver units to thecommunication with the optical communication apparatus 110_c. It istherefore possible to efficiently allocate the resources in the opticalcommunication network.

At this time, the optical communication apparatus 110_a and the opticalcommunication apparatus 110_b communicate with each other via thetransmission/reception port 113_1 a of the optical communicationapparatus 110_a and a transmission/reception port 113_1 b of the opticalcommunication apparatus 110_b. The optical communication apparatus 110_aand the optical communication apparatus 110_c communicate with eachother via the transmission/reception port 113_2 a of the opticalcommunication apparatus 110_a and a transmission/reception port 113_1 cof the optical communication apparatus 110_c. The optical communicationapparatus 110_b and the optical communication apparatus 110_ccommunicate with each other via a transmission/reception port 113_2 b ofthe optical communication apparatus 110_b and a transmission/receptionport 113_2 c of the optical communication apparatus 110_c.

While the case in which the transmission capacity among the opticalcommunication apparatuses 110_a to 110_c is 50% of the maximumtransmission capacity is shown in FIG. 4, the transmission capacityamong the optical communication apparatuses 110_a to 110_c may beflexibly set by changing the number of transceiver units connected tothe transmission/reception ports using the switch units 112_a to 112_c.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical transmission apparatusand the optical transmission method capable of efficiently allocatingthe resources in the optical communication network.

Second Exemplary Embodiment

Next, a second exemplary embodiment of the present invention will bedescribed. In the second exemplary embodiment, detailed configurationsof the optical transmission apparatus 1_1 described in the firstexemplary embodiment will be described. FIG. 5 is a block diagramshowing an optical transmission apparatus 1_2 according to the secondexemplary embodiment. As shown in FIG. 5, the optical transmissionapparatus 1_2 according to this exemplary embodiment includes aplurality of sub-carrier transmission units 11_1 to 11_m, an output unit12, and transmission ports 13_1 and 13_2.

The plurality of sub-carrier transmission units 11_1 to 11_m aresupplied with transmission data. The plurality of sub-carriertransmission units (SCS_1 to SCS_m) 11_1 to 11_m respectively generateoptical transmission signals 21_1 to 21_m to transmit transmission data.The symbol m is an integer equal to or greater than 2 and corresponds tothe number of sub-carrier transmission units. The optical transmissionsignals 21_1 to 21_m are signals to transmit the transmission data usingsub-carriers. For example, the sub-carrier transmission unit 11_1generates the optical transmission signal 21_1 using a sub-carrier SC1that corresponds to the sub-carrier transmission unit 11_1. Further, thesub-carrier transmission unit 11_2 generates the optical transmissionsignal 21_2 using a sub-carrier SC2 that corresponds to the sub-carriertransmission unit 11_2. In this way, the sub-carrier transmission units11_1 to 11_m respectively generate the optical transmission signals 21_1to 21_m using the sub-carriers SC1 to SCm respectively corresponding tothe sub-carrier transmission units 11_1 to 11_m.

The optical transmission signals 21_1 to 21_m (in other words,sub-carriers SC1 to SCm used when the optical transmission signals 21_1to 21_m are generated) can be set using a predetermined parameter. Atthis time, the parameters of the respective optical transmission signals21_1 to 21_m are allocated in such a way that they do not overlap eachother. When a plurality of parameters are used as a predeterminedparameter, the optical transmission signals 21_1 to 21_m are arranged insuch a way they do not overlap each other on a matrix having a pluralityof parameters as axes. For example, the predetermined parameter is atleast one of a wavelength, a polarization, and a time.

FIGS. 6 and 7 are diagrams each describing an arrangement of thesub-carriers. FIG. 6 shows one example of the arrangement of thesub-carriers when the wavelength and the time are used as thepredetermined parameter. In the case shown in FIG. 6, when each of thesub-carriers SC1 to SC4 is arranged on a matrix in which an X axisrepresents the wavelength and a Y axis represents the time (in thiscase, XY-plane), the sub-carriers SC1 to SC4 are arranged so that theydo not overlap with one another on the matrix plane. In the exampleshown in FIG. 6, the wavelengths of the sub-carriers SC1 to SC4 arerespectively set to λ1 to λ4 and further the sub-carriers SC1 to SC4 aretime-divided by time t1 to t4. That is, the sub-carrier SC1 can be setusing a parameter (λ1, t1), the sub-carrier SC2 can be set using aparameter (λ2, t2), the sub-carrier SC3 can be set using a parameter(λ3, t3), and the sub-carrier SC4 can be set using a parameter (λ4, t4).

Further, FIG. 7 shows one example of the arrangement of the sub-carrierswhen the wavelength and the polarization are used as the predeterminedparameter. In the case shown in FIG. 7, when the sub-carriers SC1 to SC4are arranged on a matrix in which an X axis represents the wavelengthand a Y axis represents the polarization (in this case, XY-plane), thesub-carriers SC1 to SC4 are arranged so that they do not overlap withone another on the matrix plane. In the example shown in FIG. 7, thewavelengths of the sub-carriers SC1 to SC4 are respectively set to λ1 toλ4 and further the polarization of each of the sub-carriers SC1 to SC4is set to one of an X-polarization and a Y-polarization. That is, thesub-carrier SC1 can be set using the parameter (λ1, X-polarization), thesub-carrier SC2 can be set using the parameter (λ2, Y-polarization), thesub-carrier SC3 can be set using the parameter (λ3, X-polarization), andthe sub-carrier SC4 can be set using the parameter (λ4, Y-polarization).

As described above, by allocating the parameters of the opticaltransmission signals 21_1 to 21_m in such a way that they do not overlapwith one another, it is possible to reduce the influence of the mutualinterference among the sub-carriers. While the case in which therespective sub-carriers have been set using two parameters have beendescribed in FIGS. 6 and 7, the respective sub-carriers may be set usingthree or more parameters in this exemplary embodiment.

When the wavelength is included as the above parameter, the plurality ofsub-carrier transmission units 11_1 to 11_m may include light sources(light sources that output light having a single wavelength (not shown))to generate the sub-carriers SC1 to SCm, respectively. For example, thelight source can be formed of a laser diode.

Further, the sub-carrier transmission units 11_1 to 11_m mayrespectively modulate the optical transmission signals 21_1 to 21_musing a predetermined modulation system. The modulation system may be,for example, amplitude shift keying (ASK), frequency shift keying (FSK),phase shift keying (PSK), quadrature amplitude modulation (QAM), orquadri-phase shift keying (QPSK). The quadrature amplitude modulation(QAM) may be, for example, 16-QAM, 64-QAM, 128-QAM, or 256-QAM.

The output unit 12 selectively outputs the optical transmission signals21_1 to 21_m respectively output from the plurality of sub-carriertransmission units 11_1 to 11_m to the plurality of transmission ports(PS_1, PS_2) 13_1 and 13_2. The transmission ports 13_1 and 13_2respectively correspond to the first path 26_1 and the second path 26_2described in the first exemplary embodiment. At this time, the outputunit 12 outputs an optical transmission signal 22_1 in which a pluralityof optical transmission signals are multiplexed to the transmission port13_1. For example, when the output unit 12 outputs the opticaltransmission signals 21_1 to 21_5 to the transmission port 13_1, theoptical transmission signal 22_1 in which the optical transmissionsignals 21_1 to 21_5 are multiplexed is output to the transmission port13_1. In a similar way, the output unit 12 outputs an opticaltransmission signal 22_2 in which a plurality of optical transmissionsignals are multiplexed to the transmission port 13_2. For example, whenthe output unit 12 outputs the optical transmission signals 21_6 to21_10 to the transmission port 13_2, the optical transmission signal22_2 in which the optical transmission signals 21_6 to 21_10 aremultiplexed is output to the transmission port 13_2.

The output unit 12 is able to arbitrarily and dynamically switch theoptical transmission signals 21_1 to 21_m to be supplied to thetransmission ports 13_1 and 13_2. For example, the output unit 12 iscontrolled using control means (not shown).

The plurality of transmission ports 13_1 and 13_2 are configured to beable to transmit the optical transmission signals 22_1 and 22_2 outputfrom the output unit 12 (in other words, the optical transmissionsignals 21_1 to 21_m output from the sub-carrier transmission units 11_1to 11_m). That is, the transmission port 13_1 outputs an opticaltransmission signal 23_1 (same as the optical transmission signal 22_1)to the first optical reception apparatus (not shown), which is aconnection destination. Further, the transmission port 13_2 outputs anoptical transmission signal 23_2 (same as the optical transmissionsignal 22_2) to the second optical reception apparatus (not shown),which is a connection destination.

In this exemplary embodiment, the case in which the optical transmissionapparatus 1_2 includes two transmission ports 13_1 and 13_2 has beendescribed as an example. However, the number of transmission portsincluded in the optical transmission apparatus 1_2 may be three or more.When the number of transmission ports is three or more, the output unit12 is able to selectively output the optical transmission signals 21_1to 21_m respectively output from the plurality of sub-carriertransmission units 11_1 to 11_m to the three or more transmission ports.

As described above, in the optical transmission apparatus according tothis exemplary embodiment, as shown in FIG. 5, the plurality oftransmission ports 13_1 and 13_2 and the output unit 12 are provided andthe optical transmission signals 21_1 to 21_m respectively output fromthe plurality of sub-carrier transmission units 11_1 to 11_m areselectively output to the transmission ports 13_1 and 13_2 using theoutput unit 12. Accordingly, when there is a sub-carrier transmissionunit 11_m that is not used while data is being transmitted to the firstoptical reception apparatus (not shown) via the transmission port 13_1,for example, data can be transmitted to the second optical receptionapparatus (not shown) via the transmission port 13_2 using the unusedsub-carrier transmission unit 11_m.

Further, by dynamically changing the optical transmission signals 21_1to 21_m to be supplied to the transmission ports 13_1 and 13_2 using theoutput unit 12, it is possible to dynamically adjust the transmissioncapacity in the communication via the transmission port 13_1 and thetransmission capacity in the communication via the transmission port13_2.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical transmission apparatusand the optical transmission method capable of efficiently allocatingthe resources in the optical communication network.

Third Exemplary Embodiment

Next, a third exemplary embodiment of the present invention will bedescribed. FIG. 8 is a block diagram showing an optical transmissionapparatus 1_3 according to this exemplary embodiment. The opticaltransmission apparatus 1_3 according to this exemplary embodiment isdifferent from the optical transmission apparatus 1_2 according to thesecond exemplary embodiment in that the optical transmission apparatus1_3 according to this exemplary embodiment includes a light source 14, asub-carrier generation unit 15, and a signal converter 16. Since theother configurations are similar to those of the optical transmissionapparatus 1_2 described in the second exemplary embodiment, the samecomponents are denoted by the same reference symbols and overlappingdescriptions will be omitted.

As shown in FIG. 8, the optical transmission apparatus 1_3 according tothis exemplary embodiment includes a plurality of sub-carriertransmission units 11′_1 to 11′_m, an output unit 12, transmission ports13_1 and 13_2, a light source 14, a sub-carrier generation unit 15, anda signal converter 16.

The light source 14 is a light source that outputs a single carrier C1(light having a single wavelength) and may be formed of, for example, alaser diode. The carrier C1 generated by the light source 14 is outputto the sub-carrier generation unit 15.

The sub-carrier generation unit 15 generates a plurality of sub-carriersSC1 to SCm using the carrier C1 generated in the light source 14 andsupplies the sub-carriers SC1 to SCm that have been generated to thesub-carrier transmission units 11′_1 to 11′_m, respectively. At thistime, the sub-carrier generation unit 15 may generate the plurality ofsub-carriers SC1 to SCm by modulating the carrier C1 generated in thelight source 14 using a predetermined modulation system.

For example, the sub-carrier generation unit 15 may generate theplurality of sub-carriers SC1 to SCm that are perpendicular to eachother by modulating the carrier C1 generated in the light source 14using orthogonal frequency division multiplexing (OFDM). Alternatively,the sub-carrier generation unit 15 may generate the plurality ofsub-carriers SC1 to SCm using a Nyquist WDM system. By generating theplurality of sub-carriers SC1 to SCm using the OFDM system or theNyquist WDM system as stated above, it is possible to narrow down thefrequency intervals to symbol rate intervals and to improve thefrequency use efficiency in the communication using the SuperChanneltechnology.

When the sub-carriers are generated using light sources included in therespective sub-carrier transmission units 11_1 to 11_m (see the secondexemplary embodiment), for example, the intervals between thesub-carriers SC1 to SC4 become wide, as shown in FIG. 9. On the otherhand, when the sub-carriers are generated by modulating the carrier C1generated by the light source 14 in the OFDM system as in this exemplaryembodiment, as shown in FIG. 10, the intervals between the sub-carriersSC1 to SC4 become narrower than those shown in FIG. 9, whereby it ispossible to enhance the frequency use efficiency.

At this time, it is preferable that the intervals between thesub-carriers SC1 to SCm be constant. That is, when the wavelengthintervals between the respective sub-carriers SC1 to SCm vary, it isrequired to consider the change in the wavelengths of the respectivesub-carriers SC1 to SCm. In this case, the frequency use efficiency isreduced. Therefore, in the optical transmission apparatus 1_3 accordingto this exemplary embodiment, a single light source is used as the lightsource 14. It is therefore possible to make the intervals of therespective sub-carriers SC1 to SCm become constant.

The signal converter 16 serial-parallel converts transmission data DS1and DS2 that have been input and outputs data DP1 to DPm obtained byserial-parallel converting the transmission data DS1 and DS2 to thesub-carrier transmission units 11′_1 to 11′_m, respectively. Thesub-carrier transmission unit 11′_1 generates an optical transmissionsignal 21_1 to transmit the data DP1 using the sub-carrier SC1. Thesub-carrier transmission unit 11′_2 generates an optical transmissionsignal 21_2 to transmit the data DP2 using the sub-carrier SC2. In thisway, the sub-carrier transmission unit 11′_m generates the opticaltransmission signal 21_m to transmit the data DPm using the sub-carrierSCm.

Accordingly, in the optical transmission apparatus 1_3 according to thisexemplary embodiment, the plurality of sub-carrier transmission units11′_1 to 11′_m are able to transmit the transmission data DP1 to DPm inparallel using the sub-carriers SC1 to SCm respectively corresponding tothe sub-carrier transmission units 11′_to 11′_m.

That is, the respective sub-carrier transmission units of the pluralityof sub-carrier transmission units 11′_1 to 11′_m that transmit theoptical transmission signal 22_1 via the transmission port 13_1 are ableto transmit the first data in parallel. Further, the respectivesub-carrier transmission units of the plurality of sub-carriertransmission units 11′_1 to 11′_m that transmit the optical transmissionsignal 22_2 via the transmission port 13_2 are able to transmit thesecond data in parallel.

Specifically, it is assumed, for example, that the optical transmissionapparatus 1_3 includes the sub-carrier transmission units 11′_1 to11′_10 and the sub-carrier transmission units 11′_to 11′_16 of thesub-carrier transmission units 11′_1 to 11′_10 transmit the first dataDS1 via the transmission port 13_1. It is further assumed that thesub-carrier transmission units 11′_17 to 11′_10 transmit the second dataDS2 via the transmission port 13_2.

In this case, the signal converter 16 serial-parallel converts the firstdata DS1 that has been input and outputs the first data DP1 to DP6obtained by serial-parallel converting the first data DS1 to thesub-carrier transmission units 11′_1 to 11′_6, respectively. Thesub-carrier transmission units 11′_1 to 11′_6 respectively generate theoptical transmission signals 21_1 to 21_6 to transmit the first data DP1to DP6 using the sub-carriers SC1 to SC6, respectively. The output unit12 outputs the optical transmission signals 21_1 to 21_6 that have beengenerated to the transmission port 13_1. Accordingly, the multiplexedoptical transmission signal 22_1 is output from the transmission port13_1. Therefore, the sub-carrier transmission units 11′_1 to 11′_6 areable to transmit the first data DS1 that has been serial-parallelconverted via the transmission port 13_1 in parallel. At this time, thedata width of the transmission data transmitted via the transmissionport 13_1 corresponds to the number of sub-carrier transmission units11′_1 to 11′_6 connected to the transmission port 13_1 (that is, dataDP1 to DP6).

Further, the signal converter 16 serial-parallel converts the seconddata DS2 that has been input and outputs the second data DP7 to DP10obtained by serial-parallel converting the second data DS2 to thesub-carrier transmission units 11′_7 to 11′_10, respectively. Thesub-carrier transmission units 11′_7 to 11′_10 respectively generate theoptical transmission signals 21_7 to 21_10 to transmit the second dataDP7 to DP10 using the sub-carriers SC7 to SC10, respectively. The outputunit 12 outputs the optical transmission signals 21_7 to 21_10 that havebeen generated to the transmission port 13_2. Accordingly, themultiplexed optical transmission signal 22_2 is output from thetransmission port 13_2. Therefore, the sub-carrier transmission units11′_7 to 11′_10 are able to transmit the second data DS2 that has beenserial-parallel converted via the transmission port 13_2 in parallel. Atthis time, the data width of the transmission data transmitted via thetransmission port 13_2 corresponds to the number of sub-carriertransmission units 11′_7 to 11′_10 connected to the transmission port13_2 (that is, data DP7 to DP10).

The data width of the transmission data transmitted via the transmissionport 13_1 and the data width of the transmission data transmitted viathe transmission port 13_2 can be adjusted by changing the outputdestinations of the respective optical transmission signals 21_1 to 21_moutput from the plurality of sub-carrier transmission units 11′_1 to11′_m using the output unit 12.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical transmission apparatusand the optical transmission method capable of efficiently allocatingthe resources in the optical communication network.

Fourth Exemplary Embodiment

Next, a fourth exemplary embodiment of the present invention will bedescribed. FIG. 11 is a block diagram showing an optical transmissionapparatus 1_4 according to this exemplary embodiment. In the opticaltransmission apparatus 1_4 according to this exemplary embodiment, aspecific configuration example of the output unit 12 included in theoptical transmission apparatuses 1_1 to 1_3 described in the first tothird exemplary embodiments is shown. Since the other configurations aresimilar to those of the optical transmission apparatuses 1_1 to 1_3described in the first to third exemplary embodiments, the samecomponents are denoted by the same reference symbols and overlappingdescriptions will be omitted.

As shown in FIG. 11, an output unit 12_1 included in the opticaltransmission apparatus 1_4 according to this exemplary embodimentincludes a switch unit 30 and optical multiplexers 31_1 and 31_2. Theswitch unit 30 switches the output destinations of the opticaltransmission signals 21_1 to 21_m respectively output from thesub-carrier transmission units 11_1 to 11_m to one of the opticalmultiplexer 31_1 and the optical multiplexer 31_2. The switch unit 30may be formed, for example, using an optical matrix switch having minputs and m×2 outputs. Here, the m inputs of the switch unit 30correspond to the number of optical transmission signals 21_1 to 21_m.For example, the switch unit 30 is controlled using control means (notshown).

The plurality of optical multiplexers 31_1 and 31_2 are provided tocorrespond to the transmission ports 13_1 and 13_2, respectively, andmultiplex the optical transmission signals 21_1 to 21_m output from theswitch unit 30. That is, the optical multiplexer 31_1 multiplexes theoptical transmission signals output from the switch unit 30 to produce amultiplexed optical transmission signal 22_1 and outputs the multiplexedoptical transmission signal 22_1 to the transmission port 13_1. In asimilar way, the optical multiplexer 31_2 multiplexes the opticaltransmission signals output from the switch unit 30 to produce amultiplexed optical transmission signal 22_2 and outputs the multiplexedoptical transmission signal 22_2 to the transmission port 13_2.

As described above, in the optical transmission apparatus 1_4 accordingto this exemplary embodiment, the output unit 12_1 is formed using theswitch unit 30 and the optical multiplexers 31_1 and 31_2. It istherefore possible to dynamically switch the optical transmissionsignals 21_1 to 21_m to be supplied to the transmission ports 13_1 and13_2.

The switch unit 30 may include a plurality of optical switches SW_1 toSW_m as shown in an output unit 12_2 included in an optical transmissionapparatus 1_5 shown in FIG. 12. In this case, the plurality of opticalswitches SW_1 to SW_m are provided to correspond to the sub-carriertransmission units 11_1 to 11_m, respectively, and switch the outputdestinations of the optical transmission signals 21_1 to 21_mrespectively output from the sub-carrier transmission units 11_1 to 11_mto the optical multiplexer 31_1 or the optical multiplexer 31_2.

For example, the optical switch SW_1 is provided to correspond to thesub-carrier transmission unit 11_1 and outputs the optical transmissionsignal 21_1 output from the sub-carrier transmission unit 11_1 to one ofthe optical multiplexer 31_1 and the optical multiplexer 31_2. Theoptical switch SW_2 is provided to correspond to the sub-carriertransmission unit 11_2 and outputs the optical transmission signal 21_2output from the sub-carrier transmission unit 11_2 to one of the opticalmultiplexer 31_1 and the optical multiplexer 31_2. The optical switchesSW_1 to SW_m are controlled using control means (not shown).

Further, the output unit may include an optical multiplexer 32 and anoptical demultiplexer 33 as shown in an output unit 12_3 included in anoptical transmission apparatus 1_6 shown in FIG. 13. In this case, theoptical multiplexer 32 multiplexes the optical transmission signals 21_1to 21_m respectively output from the sub-carrier transmission units 11_1to 11_m to produce a multiplexed optical signal 25 and outputs themultiplexed optical signal 25 to the optical demultiplexer 33. Theoptical demultiplexer 33 selectively outputs the respective opticaltransmission signals 21_1 to 21_m included in the multiplexed opticalsignal 25 output from the optical multiplexer 32 to the transmissionport 13_1 or 13_2.

For example, the optical demultiplexer 33 outputs the opticaltransmission signal 21_1 included in the multiplexed optical signal 25to one of the transmission port 13_1 and the transmission port 13_2.Further, the optical demultiplexer 33 outputs the optical transmissionsignal 21_2 included in the multiplexed optical signal 25 to one of thetransmission port 13_1 and the transmission port 13_2.

For example, the optical demultiplexer 33 may selectively output therespective optical transmission signals 21_1 to 21_m included in themultiplexed optical signal 25 to the transmission port 13_1 or 13_2according to the wavelength.

Fifth Exemplary Embodiment

Next, a fifth exemplary embodiment according to the present inventionwill be described. FIG. 14 is a block diagram showing an opticalreception apparatus 2_1 according to the fifth exemplary embodiment. Asshown in FIG. 14, the optical reception apparatus 2_1 according to thisexemplary embodiment includes a switch unit 42, a first reception unit43_1, and a second reception unit 43_2. In the following description,the first and second reception units may be referred to as sub-carrierreception units.

The switch unit 42 receives optical reception signals 51_1 and 51_2 thathave been input and selectively outputs sub-carrier reception signals52_1 and 52_2 included therein to the first reception unit 43_1 and thesecond reception unit 43_2. In other words, the switch unit 42 is ableto arbitrarily and dynamically switch the output destinations (first andsecond reception units 43_1 and 43_2) of the sub-carrier receptionsignals included in the optical reception signals 51_1 and 51_2. Forexample, the switch unit 42 is controlled using control means (notshown).

The first reception unit 43_1 receives data transmitted using thesub-carrier reception signal 52_1. The second reception unit 43_2receives data transmitted using the sub-carrier reception signal 52_2.The first reception unit 43_1 and the second reception unit 43_2 includedetectors (not shown) to detect the sub-carrier reception signals 52_1and 52_2, respectively. Each of the detectors may include a localoscillator.

In the optical reception apparatus 2_1 according to this exemplaryembodiment, when the first sub-carrier reception signal 52_1 and thesecond sub-carrier reception signal 52_2 share the set of information,the switch unit 42 receives the first sub-carrier reception signal 52_1and the second sub-carrier reception signal 52_2 via one path. Forexample, the switch unit 42 is able to receive the first sub-carrierreception signal 52_1 and the second sub-carrier reception signal 52_2via one path by receiving the optical reception signal 51_1 includingthe first sub-carrier reception signal 52_1 and the second sub-carrierreception signal 52_2. At this time, the switch unit 42 outputs thefirst sub-carrier reception signal 52_1 to the first reception unit 43_1and the second sub-carrier reception signal 52_2 to the second receptionunit 43_2.

On the other hand, when the first sub-carrier reception signal 52_1 andthe second sub-carrier reception signal 52_2 do not share the set ofinformation, the switch unit 42 receives the first sub-carrier receptionsignal 52_1 and the second sub-carrier reception signal 52_2 via pathsdifferent from each other. For example, when the optical receptionsignal 51_1 includes the first sub-carrier reception signal 52_1 and theoptical reception signal 51_2 includes the second sub-carrier receptionsignal 52_2, the switch unit 42 is able to receive the first sub-carrierreception signal 52_1 and the second sub-carrier reception signal 52_2via paths different from each other by receiving the optical receptionsignal 51_1 and the optical reception signal 51_2. At this time, theswitch unit 42 outputs the first sub-carrier reception signal to thefirst reception unit 43_1 and the second sub-carrier reception signal tothe second reception unit 43_2.

The case in which the first sub-carrier reception signal 52_1 and thesecond sub-carrier reception signal 52_2 share the set of informationincludes, for example, a case in which desired data is transmitted inparallel using the first sub-carrier reception signal 52_1 and thesecond sub-carrier reception signal 52_2.

On the other hand, the case in which the first sub-carrier receptionsignal 52_1 and the second sub-carrier reception signal 52_2 do notshare the set of information includes, for example, a case in which thefirst sub-carrier reception signal 52_1 and the second sub-carrierreception signal 52_2 independently transmit desired data (e.g., a casein which a first optical transmission apparatus (not shown) transmitsthe first data using the first sub-carrier reception signal 52_1 and asecond optical transmission apparatus (not shown) transmits the seconddata to the second sub-carrier reception signal 52_2). At this time, theoptical reception apparatus 2_1 receives the first sub-carrier receptionsignal 52_1 transmitted from the first optical transmission apparatus(not shown) via the first path and the second sub-carrier receptionsignal 52_2 transmitted from the second optical transmission apparatus(not shown) via the second path.

As described above, in the optical reception apparatus 2_1 according tothis exemplary embodiment, the first sub-carrier reception signal 52_1and the second sub-carrier reception signal 52_2 are selectively outputto the first reception unit 43_1 and the second reception unit 43_2using the switch unit 42.

Due to the reason same as that described in the first exemplaryembodiment, it is possible to provide the optical reception apparatusand the optical reception method capable of efficiently allocating theresources in the optical communication network.

Sixth Exemplary Embodiment

Next, a sixth exemplary embodiment of the present invention will bedescribed. FIG. 15 is a block diagram showing an optical receptionapparatus 2_2 according to the sixth exemplary embodiment. In the sixthexemplary embodiment, detailed configurations of the optical receptionapparatus 2_1 described in the fifth exemplary embodiment will bedescribed. As shown in FIG. 15, the optical reception apparatus 2_2according to this exemplary embodiment includes a plurality of receptionports 41_1 and 41_2, a switch unit 42, sub-carrier reception units 43_1to 43_m, and a signal processing unit 45.

The plurality of reception ports (PR_1 and PR_2) 41_1 and 41_2 receivemultiplexed optical reception signals 50_1 and 50_2 supplied to theoptical reception apparatus 2_2, respectively, and output opticalreception signals 51_1 and 51_2 that have been received to the switchunit 42. The reception ports 41_1 and 41_2 are able to respectivelyreceive the optical reception signals 50_1 and 50_2 transmitted fromoptical transmission apparatuses different from each other. For example,the reception port 41_1 is able to receive the optical reception signal50_1 transmitted from the first optical transmission apparatus (notshown) and the reception port 41_2 is able to receive the opticalreception signal 50_2 transmitted from the second optical transmissionapparatus (not shown).

The switch unit 42 selectively outputs sub-carrier reception signals52_1 to 52_m included in the optical reception signals 51_1 and 51_2received by the plurality of reception ports 41_1 and 41_2 to theplurality of sub-carrier reception units (SCR_1 to SCR_m) 43_1 to 43_m,respectively. In other words, the optical reception signals 51_1 and51_2 that have been multiplexed are separated into the sub-carrierreception signals 52_1 to 52_m in the switch unit 42. The sub-carrierreception signals 52_1 to 52_m that have been separated are output tothe sub-carrier reception units 43_1 to 43_m respectively correspondingto the sub-carrier reception signals 52_1 to 52_m (that is, thesub-carrier reception units that can receive the sub-carrier receptionsignals having wavelengths different from one another). At this time,one sub-carrier reception signal 52_m is input to one sub-carrierreception unit 43_m.

The switch unit 42 is able to arbitrarily and dynamically switch theoutput destinations (sub-carrier reception units 43_1 to 43_m) of therespective sub-carrier reception signals 52_1 to 52_m. For example, theswitch unit 42 is controlled using control means (not shown).

The sub-carrier reception unit 43_1 receives data transmitted using thesub-carrier reception signal 52_1. The sub-carrier reception unit 43_2receives data transmitted using the sub-carrier reception signal 52_2.In this way, the sub-carrier reception unit 43_m receives datatransmitted using the sub-carrier reception signal 52_m. The sub-carrierreception units 43_1 to 43_m include detectors (not shown) torespectively detect the sub-carrier reception signals 52_1 to 52_m. Eachof the detectors may include a local oscillator. That is, thesub-carrier reception units 43_1 to 43_m are able to receive thesub-carrier reception signals 52_1 to 52_m respectively corresponding tothe sub-carrier reception units 43_1 to 43_m by making the localoscillation light generated in the respective local oscillators and thesub-carrier reception signals 52_1 to 52_m that have been inputinterfere with each other.

The sub-carrier reception signals 52_1 to 52_m may be modulated using apredetermined modulation system. In this case, the sub-carrier receptionunits 43_1 to 43_m include circuits for reading out data from thesub-carrier reception signals 52_1 to 52_m modulated by a predeterminedmodulation system. The predetermined modulation system may include, forexample, amplitude shift keying (ASK), frequency shift keying (FSK),phase shift keying (PSK), quadrature amplitude modulation (QAM), orquadri-phase shift keying (QPSK). Quadrature amplitude modulation (QAM)may be, for example, 16-QAM, 64-QAM, 128-QAM, or 256-QAM.

Further, in the optical reception apparatus 2_2 according to thisexemplary embodiment, the sub-carrier reception units of the pluralityof sub-carrier reception units 43_1 to 43_m that have received thesub-carrier reception signal (optical reception signal 50_1) via thereception port 41_1 are able to receive the first data that has beenserial-parallel converted in parallel. Further, the sub-carrierreception units of the plurality of sub-carrier reception units 43_1 to43_m that have received the sub-carrier reception signal (opticalreception signal 50_2) via the second reception port 41_2 are able toreceive the second data that has been serial-parallel converted. Inother words, the respective sub-carrier reception signals included inthe optical reception signal 50_1 received via the reception port 41_1share the set of information. Further, the respective sub-carrierreception signals included in the optical reception signal 50_2 receivedvia the reception port 41_2 share the set of information.

Specifically, it is assumed, for example, that the optical receptionapparatus 2_2 includes sub-carrier reception units 43_1 to 43_10 and thesub-carrier reception units 43_1 to 43_6 of the sub-carrier receptionunits 43_1 to 43_10 receive the first data via the reception port 41_1.It is further assumed that the sub-carrier reception units 43_7 to 43_10receive the second data via the reception port 41_2.

In this case, the optical reception apparatus 2_2 receives the opticalreception signal 50_1 transmitted from the first optical transmissionapparatus (not shown) via the reception port 41_1. The sub-carrierreception units 43_1 to 43_6 respectively receive sub-carrier receptionsignals 52_1 to 52_6 included in the optical reception signal 50_1,whereby it is possible to receive the first data (data serial-parallelconverted by the first optical transmission apparatus) in parallel. Thefirst data that has been transmitted in parallel can be converted intoserial data by the signal processing unit 45 provided in the latterstage.

In a similar way, the optical reception apparatus 2_2 receives theoptical reception signal 50_2 transmitted from the second opticaltransmission apparatus (not shown) via the reception port 41_2. Thesub-carrier reception units 43_7 to 43_10 respectively receive thesub-carrier reception signals 52_7 to 52_10 included in the opticalreception signal 50_2, whereby it is possible to receive the second data(data that has been serial-parallel converted by the second opticaltransmission apparatus) in parallel. The second data that has beentransmitted in parallel can be converted into serial data by the signalprocessing unit 45 provided in the latter stage.

For example, each of the sub-carrier reception units 43_1 to 43_mincludes a photoelectric converter (not shown). The respectivephotoelectric converters convert the sub-carrier reception signals 52_1to 52_m into electric signals and output the electric signals to thesignal processing unit 45 as reception signals 53_1 to 53_m. Aphotodiode may be used, for example, as the photoelectric converter.

The signal processing unit 45 performs predetermined processing on thereception signals 53_1 to 53_m output from the sub-carrier receptionunits 43_1 to 43_m to generate data. Further, the signal processing unit45 may compensate for the influence of mutual interference among thesub-carrier reception signals 52_1 to 52_m. That is, by concurrentlyprocessing the sub-carrier reception units 43_1 to 43_m in the signalprocessing unit 45, compensation of crosstalk and compensation of anon-linear optical effect (e.g., cross-phase modulation (XPM), four wavemixing (FWM)) may be carried out, for example. For example, the signalprocessing unit 45 may compensate for the influence of the mutualinterference among the sub-carrier reception signals 52_1 to 52_m bycontrolling the local oscillators included in the respective sub-carrierreception units 43_1 to 43_m according to the sub-carrier receptionsignals 52_1 to 52_m.

In the SuperChannel technology, the plurality of wavelengths(sub-carriers) are used in the bandwidth of one channel and thewavelengths are multiplexed with a high density. Therefore, there is alarge influence of the mutual interference among the sub-carriers. Inthe optical reception apparatus according to this exemplary embodiment,the plurality of different sub-carriers are received by one opticalreception apparatus and the neighboring sub-carriers that have aninfluence on one sub-carrier can be concurrently monitored. It istherefore possible to set compensation parameters for compensating forthe influence of the mutual interference among the sub-carrier receptionsignals.

In this exemplary embodiment, the case in which the optical receptionapparatus 2_2 includes two reception ports 41_1 and 41_2 has beendescribed. However, the number of reception ports included in theoptical reception apparatus 2_2 may be three or more.

Similar to the case described in the first exemplary embodiment, if theoptical reception apparatus includes only one reception port, thefollowing problem occurs. That is, if there are unused sub-carrierreception units while the optical reception apparatus is receiving datafrom the first optical transmission apparatus (not shown) via onereception port, the unused sub-carrier reception units cannot be usedand the resources are wasted. That is, when there is only one receptionport, it is impossible to receive data from another optical transmissionapparatus using the unused sub-carrier reception units and the unusedsub-carrier reception units are wasted.

In the optical reception apparatus 2_2 according to this exemplaryembodiment, as shown in FIG. 15, the plurality of reception ports 41_1and 41_2 and the switch unit 42 are provided and the sub-carrierreception signals 52_1 to 52_m included in the optical reception signals51_1 and 51_2 received by the plurality of reception ports 41_1 and 41_2are selectively output to the plurality of sub-carrier reception units43_1 to 43_m using the switch unit 42. Therefore, when there are unusedsub-carrier reception units, for example, it is possible to receive theoptical reception signal from another optical transmission apparatus(not shown) via a free reception port and the unused sub-carrierreception units are able to receive the data using this opticalreception signal.

While the case in which one sub-carrier reception signal 52_m is inputto one sub-carrier reception unit 43_m has been described above, theoptical reception apparatus 2_2 according to this exemplary embodimentmay be configured in such a way that a plurality of sub-carrierreception signals are input to one sub-carrier reception unit 43_m andone sub-carrier reception unit 43_m selectively receives the pluralityof sub-carrier reception signals. In this case, by providing a localoscillator (not shown) in each of the sub-carrier reception units 43_1to 43_m and making the local oscillation light having specificwavelengths output from the local oscillators and the plurality ofsub-carrier reception signals (multiplexed sub-carrier reception signal)that have been input interfere with each other, it is possible toselectively receive a predetermined sub-carrier reception signal (i.e.,sub-carrier reception signal corresponding to a particular wavelength)from the plurality of sub-carrier reception signals. In this way, byallowing the plurality of sub-carrier reception signals to be input toone sub-carrier reception unit 43_m, it is possible to simplify theconfiguration of the switch unit 42.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical reception apparatusand the optical reception method capable of efficiently allocating theresources in the optical communication network.

Seventh Exemplary Embodiment

Next, a seventh exemplary embodiment of the present invention will bedescribed. FIG. 16 is a block diagram showing an optical receptionapparatus 2_3 according to this exemplary embodiment. The opticalreception apparatus 2_3 according to this exemplary embodiment isdifferent from the optical reception apparatus 2_2 according to thesixth exemplary embodiment in that a plurality of sub-carrier receptionunits share a local oscillator (LO) in the optical reception apparatus2_3 according to this exemplary embodiment. Since the otherconfigurations are similar to those of the optical reception apparatus2_2 described in the sixth exemplary embodiment, the same components aredenoted by the same reference symbols and overlapping descriptions willbe omitted.

As shown in FIG. 16, the optical reception apparatus 2_3 according tothis exemplary embodiment includes a plurality of reception ports 41_1and 41_2, a switch unit 42, sub-carrier reception units 43_1 to 43_6,local oscillators 44_1 and 44_2, and a signal processing unit 45. In theoptical reception apparatus 2_3 according to this exemplary embodiment,a plurality of sub-carrier reception units share a local oscillator.That is, the plurality of sub-carrier reception units 43_1 to 43_3 sharethe local oscillator 44_1. Further, the plurality of sub-carrierreception units 43_4 to 43_6 share the local oscillator 44_2. In theexample shown in FIG. 16, the number of sub-carrier reception units is 6(m=6). However, the number of sub-carrier reception units may be otherthan 6. In this case, the number of local oscillators may be increasedaccording to the number of sub-carrier reception units. While theexample in which the three sub-carrier reception units share one localoscillator is shown in the example shown in FIG. 16, the number ofsub-carrier reception units that share one local oscillator may be twoor four or more.

The switch unit 42 selectively outputs the sub-carrier reception signals52_1 to 52_6 included in the optical reception signals 51_1 and 51_2received by the plurality of reception ports 41_1 and 41_2 to theplurality of sub-carrier reception units 43_1 to 43_6. In other words,the optical reception signals 51_1 and 51_2 that have been multiplexedare separated into the sub-carrier reception signals 52_1 to 52_6 in theswitch unit 42. The sub-carrier reception signals 52_1 to 52_6 that havebeen separated are output to the sub-carrier reception units 43_1 to43_6 corresponding to the sub-carrier reception signals 52_1 to 52_6,respectively. At this time, one sub-carrier reception signal is input toone sub-carrier reception unit.

The switch unit 42 is able to arbitrarily and dynamically switch theoutput destinations of the respective sub-carrier reception signals 52_1to 52_6. For example, the switch unit 42 is controlled using controlmeans (not shown).

The sub-carrier reception units 43_1 to 43_6 respectively receive datatransmitted using the sub-carrier reception signals 52_1 to 52_6. Thesub-carrier reception units 43_1 to 43_6 include detectors (not shown)to detect the sub-carrier reception signals 52_1 to 52_6. At this time,the detectors included in the sub-carrier reception units 43_1 to 43_6may perform detection using the local oscillation light output the fromlocal oscillators 44_1 and 44_2.

In summary, the sub-carrier reception units 43_1 to 43_3 are able torespectively detect the sub-carrier reception signals 52_1 to 52_3 usingthe local oscillation light output from the local oscillator 44_1. Atthis time, the local oscillator 44_1 generates the local oscillationlight having wavelengths corresponding to the respective sub-carrierreception signals 52_1 to 52_3 (wavelengths that interfere with therespective sub-carrier reception signals 52_1 to 52_3). That is, whenthe wavelengths of the sub-carrier reception signals 52_1 to 52_3 areclose to each other, even when the local oscillation light output fromthe local oscillator 44_1 is a local oscillation light having a singlewavelength, the sub-carrier reception signals 52_1 to 52_3 interferewith the local oscillation light. Therefore, the sub-carrier receptionunits 43_1 to 43_3 are able to respectively detect the sub-carrierreception signals 52_1 to 52_3 using the local oscillation light outputfrom the local oscillator 44_1.

In a similar way, the sub-carrier reception units 43_4 to 43_6 are ableto respectively detect the sub-carrier reception signals 52_4 to 52_6using the local oscillation light output from the local oscillator 44_2.At this time, the local oscillator 44_2 generates the local oscillationlight having wavelengths corresponding to the respective sub-carrierreception signals 52_4 to 52_6 (wavelengths that interfere with therespective sub-carrier reception signals 52_4 to 52_6). That is, whenthe wavelengths of the sub-carrier reception signals 52_4 to 52_6 areclose to each other, even when the local oscillation light output fromthe local oscillator 44_2 is a local oscillation light having a singlewavelength, the sub-carrier reception signals 52_4 to 52_6 interferewith the local oscillation light. Therefore, the sub-carrier receptionunits 43_4 to 43_6 are able to respectively detect the sub-carrierreception signals 52_4 to 52_6 using the local oscillation light outputfrom the local oscillator 44_2. For example, the local oscillators 44_1and 44_2 may be formed using laser diodes.

For example, each of the sub-carrier reception units 43_1 to 43_6includes a photoelectric converter (not shown). The respectivephotoelectric converters convert the sub-carrier reception signals 52_1to 52_6 into electric signals and output the electric signals to thesignal processing unit 45 as reception signals 53_1 to 53_6. Thephotoelectric converter may be, for example, a photodiode.

The signal processing unit 45 performs predetermined processing on thereception signals 53_1 to 53_6 respectively output from the sub-carrierreception units 43_1 to 43_6 to generate data. Further, the signalprocessing unit 45 is able to control the local oscillators 44_1 and44_2 according to the reception signals 53_1 to 53_6 output from thesub-carrier reception units 43_1 to 43_6. In other words, the localoscillators 44_1 and 44_2 are controlled according to the sub-carrierreception signals 52_1 to 52_6 included in the optical reception signals51_1 and 51_2.

For example, when the sub-carrier reception signals corresponding to theplurality of sub-carrier reception units are not included in the opticalreception signals 51_1 and 51_2, the signal processing unit 45 may turnoff the local oscillator shared by the plurality of sub-carrierreception units. Specifically, when none of the sub-carrier receptionsignals 52_1 to 52_3 corresponding to the sub-carrier reception units43_1 to 43_3 is included in the optical reception signals 51_1 and 51_2,the local oscillator 44_1 shared by the sub-carrier reception units 43_1to 43_3 may be turned off. In a similar way, when none of thesub-carrier reception signals 52_4 to 52_6 corresponding to thesub-carrier reception units 43_4 to 43_6 is included in the opticalreception signals 51_1 and 51_2, the local oscillator 44_2 shared by thesub-carrier reception units 43_4 to 43_6 may be turned off. According tosuch a control, unnecessary local oscillators may be turned off andpower consumption in the optical reception apparatus 2_3 can be reduced.

Further, similar to the case described in the sixth exemplaryembodiment, by concurrently processing the plurality of sub-carrierreception signals in the signal processing unit 45, it is possible tocompensate for crosstalk and the non-linear optical effect (e.g.,cross-phase modulation (XPM), four wave mixing (FWM)).

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical reception apparatusand the optical reception method capable of efficiently allocating theresources in the optical communication network.

Eighth Exemplary Embodiment

Next, an eighth exemplary embodiment according to the present inventionwill be described. FIG. 17 is a block diagram showing an opticalreception apparatus 2_4 according to this exemplary embodiment. In theoptical reception apparatus 2_4 according to this exemplary embodiment,a specific configuration example of the switch unit 42 included in theoptical reception apparatuses 2_1 to 2_3 described in the fifth toseventh exemplary embodiments is shown. Since the other configurationsare similar to those of the optical reception apparatuses 2_1 to 2_3described in the fifth to seventh exemplary embodiments, the samecomponents are denoted by the same reference symbols and overlappingdescriptions will be omitted.

As shown in FIG. 17, a switch unit 42_1 included in the opticalreception apparatus 2_4 according to this exemplary embodiment includesoptical branching devices 60_1 and 60_2 and an optical changeover switch61. The optical branching devices 60_1 and 60_2 are provided tocorrespond to the reception ports 41_1 and 41_2, respectively, branchthe optical reception signals 51_1 and 51_2 respectively received by thereception ports 41_1 and 41_2, and output the signals that have beenbranched off to the optical changeover switch 61.

The optical changeover switch 61 receives the optical reception signalsbranched off by the optical branching devices 60_1 and 60_2 andselectively outputs the optical reception signals to the sub-carrierreception units 43_1 to 43_m. For example, the optical changeover switch61 may be formed using an optical matrix switch having m×2 inputs and moutputs. The m outputs of the optical changeover switch 61 correspond tothe number of sub-carrier reception units 43_1 to 43_m. For example, theoptical changeover switch 61 is controlled using control means (notshown).

As described above, in the optical reception apparatus 2_4 according tothis exemplary embodiment, the switch unit 42_1 is configured using theoptical branching devices 60_1 and 60_2 and the optical changeoverswitch 61. Therefore, it is possible to dynamically switch thesub-carrier reception signals 52_1 to 52_m respectively supplied to thesub-carrier reception units 43_1 to 43_m.

The optical changeover switch 61 may be configured using a plurality ofoptical switches SW_1 to SW_m, as shown in a switch unit 42_2 includedin an optical reception apparatus 2_5 shown in FIG. 18. In this case,the optical switches SW_1 to SW_m are provided to correspond to thesub-carrier reception units 43_1 to 43_m, respectively, select theoptical reception signals to be output to the sub-carrier receptionunits 43_1 to 43_m from the optical reception signals branched off bythe optical branching devices 60_1 and 60_2, and output the opticalreception signals to the sub-carrier reception units 43_1 to 43_m.

For example, the optical switch SW_1 is provided to correspond to thesub-carrier reception unit 43_1, selects the sub-carrier receptionsignal 52_1 corresponding to the sub-carrier reception unit 43_1 fromthe optical reception signals branched off by the optical branchingdevices 60_1 and 60_2, and outputs the sub-carrier reception signal 52_1that has been selected to the sub-carrier reception unit 43_1. Theoptical switch SW_2 is provided to correspond to the sub-carrierreception unit 43_2, selects the sub-carrier reception signal 52_2corresponding to the sub-carrier reception unit 43_2 from the opticalreception signals branched off by the optical branching devices 60_1 and60_2, and outputs the sub-carrier reception signal 52_2 that has beenselected to the sub-carrier reception unit 43_2. The respective opticalswitches SW_1 to SW_m are controlled using control means (not shown).For example, each of the optical switches SW_1 to SW_m may be formed ofa wavelength selective optical switch.

Further, like the optical reception apparatus described in the latterpart of the sixth exemplary embodiment, for example, if each of thesub-carrier reception units 43_1 to 43_m is able to selectively receivea particular sub-carrier reception signal, a plurality of sub-carrierreception signals may be input to one sub-carrier reception unit 43_m.In this case, for example, each of the optical switches SW_1 to SW_m mayoutput the plurality of sub-carrier reception signals to one sub-carrierreception unit 43_m.

Alternatively, the switch unit may be formed of an optical multiplexer62 and an optical demultiplexer 63, as shown in a switch unit 42_3included in an optical reception apparatus 2_6 shown in FIG. 19. Theoptical multiplexer 62 multiplexes the optical reception signals 51_1and 51_2 respectively received by the reception ports 41_1 and 41_2 toproduce a multiplexed optical signal 64 and outputs the multiplexedoptical signal 64 to the optical demultiplexer 63. The opticaldemultiplexer 63 selectively outputs the respective sub-carrierreception signals 52_1 to 52_m included in the multiplexed opticalsignal 64 to the sub-carrier reception units 43_1 to 43_m, respectively.

That is, the optical demultiplexer 63 outputs the sub-carrier receptionsignal 52_1 included in the multiplexed optical signal 64 to thesub-carrier reception unit 43_1. Further, the optical demultiplexer 63outputs the sub-carrier reception signal 52_2 included in themultiplexed optical signal 64 to the sub-carrier reception unit 43_2.

For example, the optical demultiplexer 63 is able to selectively outputthe sub-carrier reception signals 52_1 to 52_m included in themultiplexed optical signal 64 to the sub-carrier reception units 43_1 to43_m, respectively, according to the wavelength. In this case, theoptical demultiplexer 63 may be formed of the wavelength selectiveoptical demultiplexer 63.

Further, like the optical reception apparatus described in the latterpart of the sixth exemplary embodiment, for example, if each of thesub-carrier reception units 43_1 to 43_m is able to selectively receivea specific sub-carrier reception signal, the plurality of sub-carrierreception signals may be input to one sub-carrier reception unit 43_m.In this case, for example, the optical demultiplexer 62 may output theplurality of sub-carrier reception signals included in the multiplexedoptical signal 63 to one sub-carrier reception unit 43_m. For example,an optical branching device may be used in place of the opticaldemultiplexer 63.

Ninth Exemplary Embodiment

Next, a ninth exemplary embodiment of the present invention will bedescribed. FIG. 20 is a block diagram showing an optical communicationapparatus 3 according to this exemplary embodiment. The opticalcommunication apparatus 3 according to this exemplary embodiment is anoptical communication apparatus that can transmit and receive data andhas a configuration in which the optical transmission apparatus 1_1described in the first exemplary embodiment and the optical receptionapparatus 2_1 described in the fifth exemplary embodiment are combinedwith each other.

As shown in FIG. 20, the optical communication apparatus 3 according tothis exemplary embodiment includes a first transmission unit 11_1, asecond transmission unit 11_2, an output unit 12, a switch unit 42, afirst reception unit 43_1, and a second reception unit 43_2. The opticaltransmission signal 22_1 and the optical reception signal 51_1 can betransmitted or received via the first path. Further, the opticaltransmission signal 22_2 and the optical reception signal 51_2 can betransmitted or received via the second path.

Since the configurations and the operations of the first transmissionunit 11_1, the second transmission unit 11_2, and the output unit 12 aresimilar to those of the optical transmission apparatus 1_1 described inthe first exemplary embodiment, overlapping descriptions will beomitted. Further, since the configurations and the operations of theswitch unit 42, the first reception unit 43_1, and the second receptionunit 43_2 are similar to those of the optical reception apparatus 2_1described in the fifth exemplary embodiment, overlapping descriptionswill be omitted.

Further, also in the optical communication apparatus 3 according to thisexemplary embodiment as well, the configurations of the opticaltransmission apparatuses 1_2 to 1_6 described in the second to fourthexemplary embodiments may be applied or the configurations of theoptical reception apparatuses 2_2 to 2_6 described in the sixth toeighth exemplary embodiments may be applied.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical communicationapparatus and the optical communication method capable of efficientlyallocating the resources in the optical communication network.

Tenth Exemplary Embodiment

Next, a tenth exemplary embodiment of the present invention will bedescribed. FIG. 21 is a block diagram showing an optical communicationsystem according to this exemplary embodiment. As shown in FIG. 21, theoptical communication system according to this exemplary embodimentincludes an optical transmission apparatus 1 and optical receptionapparatuses 70_1 and 70_2 that communicate with the optical transmissionapparatus 1. The optical transmission apparatuses 1_1 to 1_6 describedin the first to fourth exemplary embodiments may be used as the opticaltransmission apparatus 1.

The optical transmission apparatus 1 includes a plurality of sub-carriertransmission units 11_1 to 11_m, an output unit 12, and transmissionports 13_1 and 13_2. The plurality of sub-carrier transmission units11_1 to 11_m respectively generate optical transmission signals 21_1 to21_m that transmit data using sub-carriers. The output unit 12selectively outputs the optical transmission signals 21_1 to 21_mrespectively output from the sub-carrier transmission units 11_1 to 11_mto the transmission port 13_1 or the transmission port 13_2. Since theconfiguration and the operation of the optical transmission apparatus 1are similar to those of the optical transmission apparatuses 1_1 to 1_6described in the first to fourth exemplary embodiments, overlappingdescriptions will be omitted.

The transmission port 13_1 is connected to a reception port 71_1 of theoptical reception apparatus 70_1 via an optical fiber and thetransmission port 13_2 is connected to a reception port 71_2 of theoptical reception apparatus 70_2 via an optical fiber. The opticaltransmission apparatus 1 transmits the optical transmission signal 23_1to the optical reception apparatus 70_1 via the transmission port 13_1.Further, the optical transmission apparatus 1 transmits the opticaltransmission signal 23_2 to the optical reception apparatus 70_2 via thetransmission port 13_2. The optical transmission signal 23_1 is a signalin which the plurality of optical transmission signals 21_m aremultiplexed. A reception unit 72_1 included in the optical receptionapparatus 70_1 is configured to be able to receive the multiplexedoptical transmission signal. In a similar way, the optical transmissionsignal 23_2 is a signal in which the plurality of optical transmissionsignals 21_m are multiplexed. A reception unit 72_2 included in theoptical reception apparatus 70_2 is configured to be able to receive themultiplexed optical transmission signal.

The sub-carrier transmission units of the plurality of sub-carriertransmission units 11_1 to 11_m that transmit the optical transmissionsignals via the transmission port 13_1 may transmit the first data thathas been serial-parallel converted to the optical reception apparatus70_1 in parallel. Further, the sub-carrier transmission units of theplurality of sub-carrier transmission units 11_1 to 11_m that transmitthe optical transmission signals via the transmission port 13_2 maytransmit the second data that has been serial-parallel converted to theoptical reception apparatus 70_2 in parallel.

That is, the optical transmission apparatus 1 serial-parallel convertsthe first data to be transmitted to the optical reception apparatus 70_1and generates the optical transmission signal to transmit data that havebeen serial-parallel converted by the sub-carrier transmission unit totransmit the optical transmission signal to the optical receptionapparatus 70_1. The optical reception apparatus 70_1 is able to receivedata that has been serial-parallel converted included in the opticaltransmission signal 23_1 and parallel-serial convert the received datathat has been serial-parallel converted to obtain the first data thathas been parallel-serial converted. The same is applicable to the seconddata to be transmitted to the optical reception apparatus 70_2.

Further, in the optical communication system according to this exemplaryembodiment, the transmission capacity between the optical transmissionapparatus 1 and the optical reception apparatus 70_1 is determined basedon the number of sub-carrier transmission units 11_1 to 11_m that outputthe optical transmission signals to the transmission port 13_1. In asimilar way, the transmission capacity between the optical transmissionapparatus 1 and the optical reception apparatus 70_2 is determined basedon the number of sub-carrier transmission units 11_1 to 11_m that outputthe optical transmission signals to the transmission port 13_2. In otherwords, the ratio of the transmission capacity of the opticaltransmission signal 23_1 to the transmission capacity of the opticaltransmission signal 23_2 corresponds to the ratio of the number ofsub-carrier transmission units connected to the transmission port 13_1to the number of sub-carrier transmission units connected to thetransmission port 13_2. For example, in order to increase thetransmission capacity between the optical transmission apparatus 1 andthe optical reception apparatus 70_1, the output unit 12 is controlledto increase the number of sub-carrier transmission units connected tothe transmission port 13_1.

Further, the sub-carrier of a first wavelength band may be used as thetransmission between the optical transmission apparatus 1 and theoptical reception apparatus 70_1 and the sub-carrier of a secondwavelength band may be used as the transmission between the opticaltransmission apparatus 1 and the optical reception apparatus 70_2. Thefirst wavelength band and the second wavelength band are bands whosewavelengths do not overlap each other. For example, these wavelengthbands are C band, L band, S band or the like used in the WDM.

Further, the settings of the communication between the opticaltransmission apparatus 1 and the optical reception apparatus 70_1 may bedetermined according to at least one of the distance between the opticaltransmission apparatus 1 and the optical reception apparatus 70_1, atime zone in which the communication is performed, and the state of thetransmission path between the optical transmission apparatus 1 and theoptical reception apparatus 70_1. Alternatively, the communicationbetween the optical transmission apparatus 1 and the optical receptionapparatus 70_1 may be set using at least one of the allocation of thewavelength band of the sub-carrier in the communication between theoptical transmission apparatus 1 and the optical reception apparatus70_1, the path of the optical signal, and the modulation system. Thesame is applicable to the settings of the communication between theoptical transmission apparatus 1 and the optical reception apparatus70_2.

For example, the multi-value degree for each sub-carrier may decreaseand the number of sub-carriers may increase as the communicationdistance between the optical transmission apparatus 1 and the opticalreception apparatus 70_1 increases. On the other hand, the multi-valuedegree for each sub-carrier may increase and the number of sub-carriersmay decrease as the communication distance between the opticaltransmission apparatus 1 and the optical reception apparatus 70_1decreases.

A case in which the quadrature amplitude modulation (QAM) is used willbe specifically described as an example. When the communication distancebetween the optical transmission apparatus 1 and the optical receptionapparatus 70_1 is long, the bit error rate increases when themulti-value degree for each sub-carrier increases using the modulationsystem such as 128-QAM or 256-QAM. Therefore, in this case, themulti-value degree for each sub-carrier is decreased using themodulation system such as 16-QAM or 64-QAM. Further, in this case, theamount of information included in one sub-carrier becomes small.Therefore, the number of sub-carriers is increased by the amountcorresponding to this decreased amount.

On the other hand, when the communication distance between the opticaltransmission apparatus 1 and the optical reception apparatus 70_1 isshort, it is possible to increase the multi-value degree for eachsub-carrier using the modulation system such as 128-QAM or 256-QAM. Inthis case, the amount of information included in one sub-carrier can beincreased. Therefore, the number of sub-carriers can be decreased by theamount corresponding to this increased amount.

Further, when the transmission path between the optical transmissionapparatus 1 and the optical reception apparatus 70_1 is degraded (e.g.,when tension is applied to an optical fiber), for example, themulti-value degree for each sub-carrier may decrease, for example. Inthis way, by decreasing the multi-value degree for each sub-carrier, itis possible to suppress the increase in the bit error rate.

The arrangements for the communication in the optical communicationsystem described above may be determined by the optical transmissionapparatus 1 and the optical reception apparatuses 70_1 and 70_2.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical communication systemand the method of controlling the optical communication system that canefficiently allocate the resources in the optical communication network.

Eleventh Exemplary Embodiment

Next, an eleventh exemplary embodiment of the present invention will bedescribed. FIG. 22 is a block diagram showing an optical communicationsystem according to this exemplary embodiment. As shown in FIG. 22, theoptical communication system according to this exemplary embodimentincludes an optical transmission apparatus 1, optical receptionapparatuses 70_1 and 70_2 that communicate with the optical transmissionapparatus 1, and a controller 80. Since the optical communication systemaccording to this exemplary embodiment is similar to the opticalcommunication system described in the tenth exemplary embodiment exceptthat the optical communication system according to this exemplaryembodiment includes the controller 80, overlapping descriptions will beomitted. Further, in this exemplary embodiment as well, the opticaltransmission apparatuses 1_1 to 1_6 described in the first to fourthexemplary embodiments may be used as the optical transmission apparatus1.

The controller 80 is provided to control the optical transmissionapparatus 1 and the optical reception apparatuses 70_1 and 70_2. Thatis, the controller 80 is able to control the optical transmissionapparatus 1 and the optical reception apparatuses 70_1 and 70_2according to the state of communication between the optical transmissionapparatus 1 and the optical reception apparatus 70_1 and the state ofcommunication between the optical transmission apparatus 1 and theoptical reception apparatus 70_2.

FIG. 23 is a block diagram showing a configuration example of thecontroller 80. As shown in FIG. 23, the controller 80 includes a monitorunit 81 and a configuration unit 82. The monitor unit 81 monitors thestate of communication of the optical communication system, which is thestate of communication between the optical transmission apparatus 1 andthe optical reception apparatus 70_1 and the state of communicationbetween the optical transmission apparatus 1 and the optical receptionapparatus 70_2. The configuration unit 82 configures the opticaltransmission apparatus 1 and the optical reception apparatuses 70_1 and70_2 according to the result of monitoring in the monitor unit 81.

The controller 80 is able to configure the sub-carrier transmission unitused in the communication between the optical transmission apparatus 1and the optical reception apparatus 70_1 and the sub-carriertransmission unit used in the communication between the opticaltransmission apparatus 1 and the optical reception apparatus 70_2. Atthis time, the controller 80 is able to change the sub-carriertransmission unit used in the communication with each of the opticalreception apparatuses 70_1 and 70_2 by changing the configuration of theoutput unit 12 included in the optical transmission apparatus 1.

For example, the controller 80 is able to change the transmissioncapacity between the optical transmission apparatus 1 and the opticalreception apparatus 70_1 and the transmission capacity between theoptical transmission apparatus 1 and the optical reception apparatus70_2 by controlling the number of sub-carrier transmission units 11_1 to11_m that output the optical transmission signals to the transmissionports 13_1 and 13_2.

Further, the controller 80 is able to set the wavelength band of thesub-carrier used in the communication between the optical transmissionapparatus 1 and the optical reception apparatus 70_1 and the wavelengthband of the sub-carrier used in the communication between the opticaltransmission apparatus 1 and the optical reception apparatus 70_2. Forexample, the controller 80 is able to set the wavelength bands so thatthe sub-carrier of the first wavelength band is used in thecommunication between the optical transmission apparatus 1 and theoptical reception apparatus 70_1 and the sub-carrier of the secondwavelength band is used in the communication between the opticaltransmission apparatus 1 and the optical reception apparatus 70_2. Thefirst wavelength band and the second wavelength band are bands whosewavelengths do not overlap each other. For example, these wavelengthbands are C band, L band, S band or the like used in the WDM.

Alternatively, the controller 80 is able to set the communicationbetween the optical transmission apparatus 1 and the optical receptionapparatus 70_1 according to at least one of the distance between theoptical transmission apparatus 1 and the optical reception apparatus70_1, a time zone in which the communication is performed, and the stateof the transmission path between the optical transmission apparatus 1and the optical reception apparatus 70_1. Alternatively, the controller80 may set the communication between the optical transmission apparatus1 and the optical reception apparatus 70_1 using at least one of theallocation of the wavelength band of the sub-carrier in thecommunication between the optical transmission apparatus 1 and theoptical reception apparatus 70_1, the path of the optical signal, andthe modulation system. The same is applicable to the settings of thecommunication between the optical transmission apparatus 1 and theoptical reception apparatus 70_2.

For example, the controller 80 may decrease the multi-value degree foreach sub-carrier and increase the number of sub-carriers as thecommunication distance between the optical transmission apparatus 1 andthe optical reception apparatus 70_1 increases. On the other hand, thecontroller 80 may increase the multi-value degree for each sub-carrierand decrease the number of sub-carriers as the communication distancebetween the optical transmission apparatus 1 and the optical receptionapparatus 70_1 decreases. The same is applicable to the modulationsystem in the communication between the optical transmission apparatus 1and the optical reception apparatus 70_2.

Further, the controller 80 may decrease the multi-value degree for eachsub-carrier, for example, when the transmission path between the opticaltransmission apparatus 1 and the optical reception apparatus 70_1 isdegraded (when tension is applied to an optical fiber). In this way, bydecreasing the multi-value degree for each sub-carrier, it is possibleto suppress the increase in the bit error rate. The same is applicableto the modulation system between the optical transmission apparatus 1and the optical reception apparatus 70_2.

While the optical communication system including one opticaltransmission apparatus and two optical reception apparatuses has beendescribed in this exemplary embodiment, two or more optical transmissionapparatuses and three or more optical reception apparatuses thatconstitute the optical communication system may be included. In thiscase as well, the controller 80 is able to configure the opticaltransmission apparatus and the optical reception apparatus in such a waythat the whole optical communication system is in an optimalcommunication state.

The optimal communication state may be arbitrarily determined dependingon users. The optimal communication state may be, for example, acommunication state in which the cost of communication is minimized, acommunication state in which the reliability of the communication ismaximized (that is, a communication state in which the highest priorityis given to keeping the communication, which is a communication state inwhich a redundant path is considered), a communication state in whichthe communication speed is particularly prioritized (a communicationstate that makes the path the shortest), a communication state in whichthe wavelength use efficiency becomes the maximum.

Further, the controller 80 is able to collect information regardingchanges in the state of the network reported by the optical transmissionapparatus and the optical reception apparatus (e.g., a failure in anoptical transmission path and a degradation of an optical communicationsignal) and re-configure the optical transmission apparatus and theoptical reception apparatus to follow the changes in the state of thenetwork and to make the whole optical communication system be in theoptimal communication state.

According to the present invention described above in this exemplaryembodiment, it is possible to provide the optical communication systemand the method of controlling the optical communication system capableof efficiently allocating the resources in the optical communicationnetwork. Further, it is possible to provide the optical communicationsystem and the method of controlling the optical communication systemwhich make the whole optical communication system be in the optimalcommunication state.

Twelfth Exemplary Embodiment

Next, a twelfth exemplary embodiment of the present invention will bedescribed. In this exemplary embodiment, a case in which the opticalcommunication system according to the present invention is applied to acentrally controlled network will be described. FIG. 24 is a blockdiagram showing an optical communication system according to thisexemplary embodiment. As shown in FIG. 24, the optical communicationsystem according to this exemplary embodiment includes a controller 80and a plurality of nodes A to D (85_a to 85_d). The controller 80corresponds to the controller 80 described in the eleventh exemplaryembodiment. Further, the plurality of nodes A to D (85_a to 85_d) arecomponents that form the communication network. For example, the opticaltransmission apparatuses 1_1 to 1_6 described in the first to fourthexemplary embodiments, the optical reception apparatuses 2_1 to 2_6described in the fifth to eighth exemplary embodiments, or the opticalcommunication apparatus 3 described in the ninth exemplary embodimentmay be used as the plurality of nodes A to D (85_a to 85_d).

The controller 80 monitors the state of the communication of each of thenodes 85_a to 85_d and controls the nodes 85_a to 85_d according to thestate of the communication of the respective nodes 85_a to 85_d. Thecontroller 80 outputs control signals 86_a to 86_d to control therespective nodes 85_a to 85_d to the respective nodes 85_a to 85_d.

The controller 80 is able to make arrangements for the allocation ofresources used in the respective nodes 85_a to 85_d (e.g., arrangementsfor the sub-carrier transceiver units to be used) and the path of theoptical signal. For example, the controller 80 is able to change thetransmission capacity between the node 85_a and the node 85_b bydetermining the sub-carrier to be used in the communication between thenode 85_a and the node 85_b.

Further, the controller 80 is able to set the wavelength bands of thesub-carriers used in the communication among the nodes 85_a to 85_d. Forexample, the controller 80 is able to set the wavelength bands so thatthe sub-carrier of the first wavelength band is used in thecommunication between the node 85_a and the node 85_b and thesub-carrier of the second wavelength band is used in the communicationbetween the node 85_a and the node 85_d. The first wavelength band andthe second wavelength band are bands whose wavelengths do not overlapeach other. For example, these wavelength bands are C band, L band, Sband or the like used in the WDM.

The controller 80 is also able to set the communication among the nodes85_a to 85_d according to at least one of the distance between the nodes85_a to 85_d, a time zone in which the communication is performed, andthe state of the transmission path between the nodes 85_a to 85_d. Thetime zone in which the communication is performed is, for example, apredetermined time zone (day or night), a predetermined period, or atime zone of a predetermined event (e.g., execution of backup).Alternatively, the controller 80 may set the communication among thenodes 85_a to 85_d using at least one of an allocation of the wavelengthband of the sub-carrier in the communication among the nodes 85_a to85_d, a path of the optical signal, and the modulation system.

For example, the controller 80 may decrease the multi-value degree foreach sub-carrier and increase the number of sub-carriers as thecommunication distance between the node 85_a and the node 85_bincreases. On the other hand, the controller 80 may increase themulti-value degree for each sub-carrier and decrease the number ofsub-carriers as the communication distance between the node 85_a and thenode 85_b decreases. The same is applicable to the modulation systemamong the other nodes.

Further, the controller 80 may decrease the multi-value degree for eachsub-carrier, for example, when the transmission path between the node85_a and the node 85_b is degraded (when tension is applied to anoptical fiber). In this way, by decreasing the multi-value degree foreach sub-carrier, it is possible to suppress the increase in the biterror rate. The same is applicable to the modulation system among theother nodes.

While the optical communication system including four nodes 85_a to 85_dhas been described as an example in this exemplary embodiment, thenumber of nodes that constitute the optical communication system may belarger than four.

The controller 80 is able to configure the optical transmissionapparatus and the optical reception apparatus so that the whole opticalcommunication system becomes in an optimal communication state. Theoptimal communication state may be arbitrarily determined depending onusers. The optimal communication state may be, for example, acommunication state in which the cost of communication is minimized, acommunication state in which the reliability of the communication ismaximized (that is, a communication state in which the highest priorityis given to keeping the communication, which is a communication state inwhich a redundant path is considered), a communication state in whichthe communication speed is particularly prioritized (a communicationstate that makes the path the shortest), a communication state in whichthe wavelength use efficiency becomes the maximum.

Further, the controller 80 is able to collect information regardingchanges in the state of the network reported by the optical transmissionapparatus and the optical reception apparatus (e.g., a failure in anoptical transmission path and a degradation of an optical communicationsignal) and re-configure the optical transmission apparatus and theoptical reception apparatus to follow the changes in the state of thenetwork and to make the whole optical communication system be in theoptimal communication state.

For example, when a failure occurs in a shortest path 87_1 while data isbeing transmitted from the node 85_a to the node 85_b via the shortestpath 87_1, the controller 80 is able to switch the path to a redundantpath that transmits data to the node 85_b via a path 87_2 that connectsthe node 85_a and the node 85_d, a path 87_3 that connects the node 85_dand the node 85_c, and a path 87_4 that connects the node 85_c and thenode 85_b to prevent the communication from being interrupted.

According to the present invention described above in this exemplaryembodiment, it is possible to provide the optical communication systemand the method of controlling the optical communication system capableof efficiently allocating the resources in the optical communicationnetwork. Further, it is possible to provide the optical communicationsystem and the method of controlling the optical communication systemwhich make the whole optical communication system be in the optimalcommunication state.

Thirteenth Exemplary Embodiment

Next, a thirteenth exemplary embodiment according to the presentinvention will be described. FIG. 25 is a block diagram showing anoptical communication system according to this exemplary embodiment. Asshown in FIG. 25, the optical communication system according to thisexemplary embodiment includes an optical reception apparatus 2 andoptical transmission apparatuses 75_1 and 75_2 that communicate with theoptical reception apparatus 2. The optical reception apparatuses 2_1 to2_6 described in the fifth to eighth exemplary embodiments may be usedas the as the optical reception apparatus 2.

The optical reception apparatus 2 includes reception ports 41_1 and41_2, a switch unit 42, and a plurality of sub-carrier reception units43_1 to 43_m. The reception ports 41_1 and 41_2 respectively receivemultiplexed optical reception signals 50_1 and 50_2. The switch unit 42selectively outputs the sub-carrier reception signals 52_1 to 52_mrespectively included in the optical reception signals 51_1 and 51_2respectively received by the reception ports 41_1 and 41_2 to theplurality of sub-carrier reception units 43_1 to 43_m. The plurality ofsub-carrier reception units 43_1 to 43_m receive the data included inthe respective sub-carrier reception signals 52_1 to 52_m. Since theconfiguration and the operation of the optical reception apparatus 2 aresimilar to those of the optical reception apparatuses 2_1 to 2_6described in the fifth to eighth exemplary embodiments, overlappingdescriptions will be omitted.

A transmission unit 77_1 included in the optical transmission apparatus75_1 is configured to be able to transmit the multiplexed opticaltransmission signal generated using a plurality of sub-carriers. Atransmission unit 77_2 included in the optical transmission apparatus75_2 is configured to be able to transmit the multiplexed opticaltransmission signal generated using a plurality of sub-carriers. Thereception port 41_1 is connected to a transmission port 76_1 of theoptical transmission apparatus 75_1 via an optical fiber and thereception port 41_2 is connected to a transmission port 76_2 of theoptical transmission apparatus 75_2 via an optical fiber. The opticalreception apparatus 2 receives the optical reception signal 50_1transmitted from the optical transmission apparatus 75_1 via thereception port 41_1. Further, the optical reception apparatus 2 receivesthe optical reception signal 50_2 transmitted from the opticaltransmission apparatus 75_2 via the reception port 41_2.

At this time, the respective sub-carrier reception units of theplurality of sub-carrier reception units 43_1 to 43_m that receive theoptical reception signals via the reception port 41_1 may receive firstdata transmitted from the optical transmission apparatus 75_1 (data thathas been serial-parallel converted) in parallel. Further, the respectivesub-carrier reception units of the plurality of sub-carrier receptionunits 43_1 to 43_m that receive the optical reception signals via thereception port 41_2 may receive second data transmitted from the opticaltransmission apparatus 75_2 (data that has been serial-parallelconverted) in parallel.

That is, the optical transmission apparatus 75_1 serial-parallelconverts the first data to be transmitted to the optical receptionapparatus 2 and transmits each of the pieces of data that have beenserial-parallel converted to the optical reception apparatus 2 using therespective optical transmission signals. The optical reception apparatus2 receives the sub-carrier reception signal included in the opticaltransmission signal (that is, optical reception signal 50_1) transmittedfrom the optical transmission apparatus 75_1 by the sub-carrierreception unit. By parallel-serial converting the data included in thesub-carrier reception signal, the first data that has beenparallel-serial converted can be obtained. The same is applicable to thesecond data transmitted to the optical reception apparatus 2 from theoptical transmission apparatus 75_2.

Further, in the optical communication system according to this exemplaryembodiment, the transmission capacity between the optical receptionapparatus 2 and the optical transmission apparatus 75_1 corresponds tothe number of sub-carrier reception units connected to the receptionport 41_1. In a similar way, the transmission capacity between theoptical reception apparatus 2 and the optical transmission apparatus75_2 corresponds to the number of sub-carrier reception units connectedto the reception port 41_2. For example, in order to increase thetransmission capacity between the optical reception apparatus 2 and theoptical transmission apparatus 75_1, the switch unit 42 is controlled toincrease the number of sub-carrier reception units connected to thereception port 41_1.

Further, the sub-carrier of the first wavelength band may be used as thetransmission between the optical reception apparatus 2 and the opticaltransmission apparatus 75_1 and the sub-carrier of the second wavelengthband may be used as the transmission between the optical receptionapparatus 2 and the optical transmission apparatus 75_2. The firstwavelength band and the second wavelength band are bands whosewavelengths do not overlap each other. For example, these wavelengthbands are C band, L band, S band or the like used in the WDM.

The settings of the communication between the optical receptionapparatus 2 and the optical transmission apparatus 75_1 may bedetermined according to at least one of the distance between the opticalreception apparatus 2 and the optical transmission apparatus 75_1, atime zone in which the communication is performed, and the state of thetransmission path between the optical reception apparatus 2 and theoptical transmission apparatus 75_1. Alternatively, the communicationbetween the optical reception apparatus 2 and the optical transmissionapparatus 75_1 may be set using at least one of the allocation of thewavelength band of the sub-carrier in the communication between theoptical reception apparatus 2 and the optical transmission apparatus75_1, the path of the optical signal, and the modulation system. Thesame is applicable to the settings of the communication between theoptical reception apparatus 2 and the optical transmission apparatus75_2.

For example, the multi-value degree for each sub-carrier may decreaseand the number of sub-carriers may increase as the communicationdistance between the optical reception apparatus 2 and the opticaltransmission apparatus 75_1 increases. On the other hand, themulti-value degree for each sub-carrier may increase and the number ofsub-carriers may decrease as the communication distance between theoptical reception apparatus 2 and the optical transmission apparatus75_1 decreases. The same is applicable to the modulation system in thecommunication between the optical reception apparatus 2 and the opticaltransmission apparatus 75_2.

Further, for example, when the transmission path between the opticalreception apparatus 2 and the optical transmission apparatus 75_1 isdegraded (when tension is applied to an optical fiber), for example, themulti-value degree for each sub-carrier may decrease. In this way, bydecreasing the multi-value degree for each sub-carrier, it is possibleto suppress the increase in the bit error rate.

The arrangements for the communication in the optical communicationsystem described above may be determined by the optical receptionapparatus 2 and the optical transmission apparatuses 75_1 and 75_2.Further, the optical communication system according to this exemplaryembodiment may include a controller like the optical communicationsystem described in the eleventh exemplary embodiment. In this exemplaryembodiment as well, the controller may control the optical receptionapparatus 2 and the optical transmission apparatuses 75_1 and 75_2according to the state of the communication between the opticalreception apparatus 2 and the optical transmission apparatus 75_1 andthe state of the communication between the optical reception apparatus 2and the optical transmission apparatus 75_2.

According to the invention described in this exemplary embodimentdescribed above, it is possible to provide the optical communicationsystem and the method of controlling the optical communication systemcapable of efficiently allocating the resources in the opticalcommunication network.

Fourteenth Exemplary Embodiment

Next, a fourteenth exemplary embodiment of the present invention will bedescribed. FIG. 26 is a block diagram showing an optical communicationsystem according to this exemplary embodiment. As shown in FIG. 26, theoptical communication system according to this exemplary embodimentincludes optical transmission apparatuses 1 a and 1 b and opticalreception apparatuses 2 a and 2 b.

The optical transmission apparatus 1 a includes a plurality ofsub-carrier transmission units 11 a, an output unit 12 a, andtransmission ports 13_1 a and 13_2 a. The optical transmission apparatus1 b includes a plurality of sub-carrier transmission units 11 b, anoutput unit 12 b, and transmission ports 13_1 b and 13_2 b. The opticaltransmission apparatuses 1_1 to 1_6 described in the first to fourthexemplary embodiments may be used as the optical transmissionapparatuses 1 a and 1 b. For example, the sub-carrier transmission units11 a and 11 b correspond to the plurality of sub-carrier transmissionunits 11_1 to 11_m shown in FIG. 5, the output units 12 a and 12 bcorrespond to the output unit 12 shown in FIG. 5, and the transmissionports 13_1 a, 13_2 a, 13_1 b, and 13_2 b correspond to the transmissionports 13_1 and 13_2 shown in FIG. 5.

The optical reception apparatus 2 a includes reception ports 41_1 a and41_2 a, a switch unit 42 a, and a plurality of sub-carrier receptionunits 43 a. The optical reception apparatus 2 b includes reception ports41_1 b and 41_2 b, a switch unit 42 b, and a plurality of sub-carrierreception units 43 b. The optical reception apparatuses 2_1 to 2_6described in the fifth to eighth exemplary embodiments may be used asthe optical reception apparatuses 2 a and 2 b. For example, thereception ports 41_1 a, 41_2 a, 41_1 b, and 41_2 b correspond to thereception ports 41_1 and 41_2 shown in FIG. 15, the switch units 42 aand 42 b correspond to the switch unit 42 shown in FIG. 15, and thesub-carrier reception units 43 a and 43 b correspond to the sub-carrierreception units 43_1 to 43_m shown in FIG. 15.

As shown in FIG. 26, the transmission port 13_1 a of the opticaltransmission apparatus 1 a is connected to the reception port 41_1 a ofthe optical reception apparatus 2 a. The transmission port 13_2 a of theoptical transmission apparatus 1 a is connected to the reception port41_1 b of the optical reception apparatus 2 b. The transmission port13_1 b of the optical transmission apparatus 1 b is connected to thereception port 41_2 a of the optical reception apparatus 2 a. Thetransmission port 13_2 b of the optical transmission apparatus 1 b isconnected to the reception port 41_2 b of the optical receptionapparatus 2 b.

At this time, the optical transmission apparatus 1 a transmits data tothe optical reception apparatus 2 a using an optical transmission signal23_1 a generated using the plurality of sub-carriers of the firstwavelength band. Further, the optical transmission apparatus 1 atransmits data to the optical reception apparatus 2 b using an opticaltransmission signal 23_2 a generated using the plurality of sub-carriersof the second wavelength band. Further, the optical transmissionapparatus 1 b transmits data to the optical reception apparatus 2 ausing an optical transmission signal 23_1 b generated using theplurality of sub-carriers of the second wavelength band. Further, theoptical transmission apparatus 1 b transmits data to the opticalreception apparatus 2 b using an optical transmission signal 23_2 bgenerated using the plurality of sub-carriers of the first wavelengthband. The first wavelength band and the second wavelength band are bandswhose wavelengths do not overlap each other. For example, thesewavelength bands are C band, L band, S band or the like used in the WDM.

By setting the combination of the wavelength bands of the opticaltransmission signals 23_1 a, 23_2 a, 23_1 b, and 23_2 b used in thecommunication between the optical transmission apparatuses 1 a and 1 band the optical reception apparatuses 2 a and 2 b as stated above, it ispossible to prevent the wavelength bands of the sub-carriers used in thecommunication between the optical transmission apparatuses 1 a and 1 band the optical reception apparatuses 2 a and 2 b from being overlappedeach other.

In the optical communication system according to this exemplaryembodiment as well, the settings of the communication between theoptical transmission apparatuses 1 a and 1 b and the optical receptionapparatuses 2 a and 2 b may be determined according to at least one ofthe distance between the optical transmission apparatuses 1 a and 1 band the optical reception apparatuses 2 a and 2 b, a time zone in whichthe communication is performed, and the state of the transmission pathbetween the optical transmission apparatuses 1 a and 1 b and the opticalreception apparatuses 2 a and 2 b. Alternatively, the communicationbetween the optical transmission apparatuses 1 a and 1 b and the opticalreception apparatuses 2 a and 2 b may be set using at least one of theallocation of the wavelength band of the sub-carrier in thecommunication between the optical transmission apparatuses 1 a and 1 band the optical reception apparatuses 2 a and 2 b, the path of theoptical signal, and the modulation system.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical communication systemand the method of controlling the optical communication system capableof efficiently allocating the resources in the optical communicationnetwork.

Fifteenth Exemplary Embodiment

Next, a fifteenth exemplary embodiment of the present invention will bedescribed. FIG. 27 is a block diagram showing an optical communicationsystem according to this exemplary embodiment. As shown in FIG. 27, theoptical communication system according to this exemplary embodimentincludes optical communication apparatuses 3 a to 3 d. The opticalcommunication apparatuses 3 a to 3 d are optical communicationapparatuses capable of transmitting and receiving data.

The optical communication apparatus 3 a includes a sub-carriertransceiver unit 91 a, an optical transmission/reception signal switchunit 92 a, and transmission/reception ports 93_1 a and 93_2 a. Theoptical communication apparatus 3 b includes a sub-carrier transceiverunit 91 b, an optical transmission/reception signal switch unit 92 b,and transmission/reception ports 93_1 b and 93_2 b. The opticalcommunication apparatus 3 c includes a sub-carrier transceiver unit 91c, an optical transmission/reception signal switch unit 92 c, andtransmission/reception ports 93_1 c and 93_2 c. The opticalcommunication apparatus 3 d includes a sub-carrier transceiver unit 91d, an optical transmission/reception signal switch unit 92 d, andtransmission/reception ports 93_1 d and 93_2 d. The opticalcommunication apparatus 3 described in the ninth exemplary embodiment(see FIG. 20) may be used as the optical communication apparatuses 3 ato 3 d. For more detailed configurations, see FIG. 5 (second exemplaryembodiment) and FIG. 15 (sixth exemplary embodiment).

The sub-carrier transceiver unit 91 a of the optical communicationapparatus 3 a includes the sub-carrier transmission units 11_1 to 11_mshown in FIG. 5 and the sub-carrier reception units 43_1 to 43_m shownin FIG. 15, the optical transmission/reception signal switch unit 92 aincludes the output unit 12 shown in FIG. 5 and the switch unit 42 shownin FIG. 15, and the transmission/reception ports 93_1 a and 93_2 acorrespond to the transmission ports 13_1 and 13_2 shown in FIG. 5 andthe reception ports 41_1 and 41_2 shown in FIG. 15. The same isapplicable to the other optical communication apparatuses 3 b to 3 d.

As shown in FIG. 27, the transmission/reception port 93_1 a of theoptical communication apparatus 3 a is connected to thetransmission/reception port 93_1 c of the optical communicationapparatus 3 c. The transmission/reception port 93_2 a of the opticalcommunication apparatus 3 a is connected to the transmission/receptionport 93_1 d of the optical communication apparatus 3 d. Thetransmission/reception port 93_1 b of the optical communicationapparatus 3 b is connected to the transmission/reception port 93_2 c ofthe optical communication apparatus 3 c. The transmission/reception port93_2 b of the optical communication apparatus 3 b is connected to thetransmission/reception port 93_2 d of the optical communicationapparatus 3 d.

In this case, the optical communication apparatus 3 a and the opticalcommunication apparatus 3 c communicate with each other using an opticalsignal 25_1 generated using the plurality of sub-carriers of the firstwavelength band. Further, the optical communication apparatus 3 a andthe optical communication apparatus 3 d communicate with each otherusing an optical signal 25_2 generated using the plurality ofsub-carriers of the second wavelength band. Further, the opticalcommunication apparatus 3 b and the optical communication apparatus 3 ccommunicate with each other using an optical signal 25_3 generated usingthe plurality of sub-carriers of the second wavelength band. Further,the optical communication apparatus 3 b and the optical communicationapparatus 3 d communicate with each other using an optical signal 25_4generated using the plurality of sub-carriers of the first wavelengthband. The first wavelength band and the second wavelength band are bandswhose wavelengths do not overlap each other. For example, thesewavelength bands are C band, L band, S band or the like used in the WDM.

By setting the combination of the wavelength bands of the opticalsignals 25_1 to 25_4 used in the communication among the opticalcommunication apparatuses 3 a to 3 d as stated above, it is possible toprevent the wavelength bands of the sub-carriers used in thecommunication among the optical communication apparatuses 3 a to 3 dfrom being overlapped each other.

In the optical communication system according to this exemplaryembodiment as well, the settings of the communication among the opticalcommunication apparatuses 3 a to 3 d may be determined according to atleast one of the distance between the optical communication apparatuses3 a and 3 b and the optical communication apparatuses 3 c and 3 d, atime zone in which the communication is performed, and the state of thetransmission path between the optical communication apparatuses 3 a and3 b and the optical communication apparatuses 3 c and 3 d.Alternatively, the communication between the optical communicationapparatuses 3 a and 3 b and the optical communication apparatuses 3 cand 3 d may be set using at least one of the allocation of thewavelength band of the sub-carrier in the communication between theoptical communication apparatuses 3 a and 3 b and the opticalcommunication apparatuses 3 c and 3 d, the path of the optical signal,and the modulation system.

According to the present invention described in this exemplaryembodiment, it is possible to provide the optical communication systemand the method of controlling the optical communication system that canefficiently allocate the resources in the optical communication network.

While the present invention has been described as a hardwareconfiguration in the above exemplary embodiments, the present inventionis not limited to the hardware configuration. The present invention mayalso achieve desired processing by causing a CPU (Central ProcessingUnit) to execute a computer program.

The program can be stored and provided to a computer using any type ofnon-transitory computer readable media. Non-transitory computer readablemedia include any type of tangible storage media. Examples ofnon-transitory computer readable media include magnetic storage media(such as flexible disks, magnetic tapes, hard disk drives, etc.),optical magnetic storage media (e.g., magneto-optical disks), CompactDisc Read Only Memory (CD-ROM), CD-R, CD-R/W, and semiconductor memories(such as mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flashROM, Random Access Memory (RAM), etc.). The program may be provided to acomputer using any type of transitory computer readable media. Examplesof transitory computer readable media include electric signals, opticalsignals, and electromagnetic waves. Transitory computer readable mediacan provide the program to a computer via a wired communication line(e.g., electric wires, and optical fibers) or a wireless communicationline.

While the present invention has been described with reference to theexemplary embodiments, the present invention is not limited to the aboveexemplary embodiments. Various changes that can be understood by thoseskilled in the art can be made to the configurations and the details ofthe present invention within the scope of the present invention.

REFERENCE SIGNS LIST

-   1, 1_1-1_6 OPTICAL TRANSMISSION APPARATUS-   2, 2_1-2_6 OPTICAL RECEPTION APPARATUS-   3 OPTICAL COMMUNICATION APPARATUS-   11, 11_1-11_m SUB-CARRIER TRANSMISSION UNIT-   12 OPTICAL TRANSMISSION SIGNAL SWITCH UNIT-   13 TRANSMISSION PORT-   14 LIGHT SOURCE-   15 SUB-CARRIER GENERATION UNIT-   16 SIGNAL CONVERTER-   21_1-21_m OPTICAL TRANSMISSION SIGNAL-   22_1, 22_2 OPTICAL TRANSMISSION SIGNAL-   23_1, 23_2 OPTICAL TRANSMISSION SIGNAL-   26_1 FIRST PATH-   26_2 SECOND PATH-   30 SWITCH UNIT-   31_1, 31_2 OPTICAL MULTIPLEXER-   32 OPTICAL MULTIPLEXER-   33 OPTICAL DEMULTIPLEXER-   41_1, 41_2 RECEPTION PORT-   42 SWITCH UNIT-   43_1-43_m SUB-CARRIER RECEPTION UNIT-   44_1, 44_2 LOCAL OSCILLATOR-   45 SIGNAL PROCESSING UNIT-   51_1, 51_2 OPTICAL RECEPTION SIGNAL-   52_1-52_m SUB-CARRIER RECEPTION SIGNAL-   53_1-53_6 RECEPTION SIGNAL-   60_1, 60_2 OPTICAL BRANCHING DEVICE-   61 OPTICAL CHANGEOVER SWITCH-   62 OPTICAL MULTIPLEXER-   63 OPTICAL DEMULTIPLEXER-   64 MULTIPLEXED OPTICAL SIGNAL-   80 CONTROLLER-   81 MONITOR UNIT-   82 CONFIGURATION UNIT

1. An optical transmission apparatus comprising: a first transmissionunit that transmits a first optical transmission signal; a secondtransmission unit that transmits a second optical transmission signal;and an output unit that outputs, when the first optical transmissionsignal and the second optical transmission signal share a set ofinformation, both the first optical transmission signal and the secondoptical transmission signal to one path and outputs, when the firstoptical transmission signal and the second optical transmission signaldo not share the set of information, the first optical transmissionsignal and the second optical transmission signal to paths differentfrom each other.
 2. The optical transmission apparatus according toclaim 1, wherein a predetermined parameter of a first sub-carrier usedto generate the first optical transmission signal and a predeterminedparameter of a second sub-carrier used to generate the second opticaltransmission signal are allocated in such a way that they do not overlapeach other.
 3. The optical transmission apparatus according to claim 2,wherein: the predetermined parameter comprises a plurality ofparameters, and the first sub-carrier and the second sub-carrier arearranged in such a way that they do not overlap each other on a matrixhaving the plurality of parameters as axes.
 4. The optical transmissionapparatus according to claim 2, wherein the predetermined parameter isat least one of a wavelength, a polarization, and a time.
 5. The opticaltransmission apparatus according to claim 1, wherein the first andsecond transmission units generate the first and second opticaltransmission signals having wavelengths different from each other usinglight supplied from a light source.
 6. The optical transmissionapparatus according to claim 5, wherein: the first transmission unit issupplied with a first sub-carrier from a first light source; and thesecond transmission unit is supplied with a second sub-carrier from asecond light source.
 7. The optical transmission apparatus according toclaim 5, further comprising: a single light source; and a sub-carriergeneration unit that generates first and second sub-carriers using lightgenerated in the single light source and supplies the first and secondsub-carriers that have been generated to the first and secondtransmission units, respectively.
 8. The optical transmission apparatusaccording to claim 7, wherein the sub-carrier generation unit modulateslight generated in the single light source using orthogonal frequencydivision multiplexing to generate the first and second sub-carriers thatare perpendicular to each other.
 9. The optical transmission apparatusaccording to claim 1, wherein: when the first and second transmissionunits transmit data in which a set of information is shared, data thathas been serial-parallel converted is supplied to the first and secondtransmission units, the first and second transmission units transmit thedata that has been serial-parallel converted in parallel, and the outputunit outputs both the first and second optical transmission signals tothe one path.
 10. The optical transmission apparatus according to claim1, wherein the output unit comprises: a switch unit that switches outputdestinations of the first and second optical transmission signals outputfrom the first and second transmission units; and first and secondoptical multiplexers that are provided to correspond to first and secondpaths and multiplex the first and second optical transmission signalsoutput from the switch unit.
 11. The optical transmission apparatusaccording to claim 10, wherein the switch unit comprises first andsecond optical switches that are provided to correspond to the first andsecond transmission units and switch output destinations of the firstand second optical transmission signals output from the first and secondtransmission units to the first optical multiplexer or the secondoptical multiplexer.
 12. The optical transmission apparatus according toclaim 1, wherein the output unit comprises: an optical multiplexer thatmultiplexes the first and second optical transmission signals outputfrom the first and second transmission units; and an opticaldemultiplexer that selectively outputs the first and second opticaltransmission signals included in the multiplexed optical signal outputfrom the optical multiplexer to first and second paths.
 13. An opticalreception apparatus comprising: first and second reception units thatreceive a sub-carrier reception signal; and a switch unit that outputs afirst sub-carrier reception signal and a second sub-carrier receptionsignal that have been input to the first and second reception units,wherein: when the first and second sub-carrier reception signals share aset of information, the switch unit receives the first and secondsub-carrier reception signals via one path and outputs the firstsub-carrier reception signal to the first reception unit and the secondsub-carrier reception signal to the second reception unit, and when thefirst sub-carrier reception signal and the second sub-carrier receptionsignal do not share the set of information, the switch unit receives thefirst and second sub-carrier reception signals via paths different fromeach other and outputs the first sub-carrier reception signal to thefirst reception unit and the second sub-carrier reception signal to thesecond reception unit.
 14. The optical reception apparatus according toclaim 13, further comprising a signal processing unit that processes afirst reception signal output from the first reception unit and a secondreception signal output from the second reception unit, wherein thesignal processing unit compensates for an influence of mutualinterference between the first sub-carrier reception signal and thesecond sub-carrier reception signal.
 15. The optical reception apparatusaccording to claim 14, wherein: the first and second reception unitsrespectively comprise first and second local oscillators, and the signalprocessing unit compensates for an influence of mutual interferencebetween the first sub-carrier reception signal and the secondsub-carrier reception signal by controlling the first and second localoscillators according to the first and second sub-carrier receptionsignals.
 16. The optical reception apparatus according to claim 13,wherein: each of the reception units is configured to be able to receivea plurality of sub-carrier reception signals, and each of the receptionunits makes local oscillation light generated by the local oscillatorincluded in each of the reception units and the sub-carrier receptionsignals that have been input interfere with each other to selectivelyreceive a predetermined sub-carrier reception signal from the pluralityof sub-carrier reception signals that have been input.
 17. The opticalreception apparatus according to claim 13, wherein: the plurality ofreception units including the first reception unit share a first localoscillator, the plurality of reception units including the secondreception unit share a second local oscillator, and the first and secondlocal oscillators are controlled according to the sub-carrier receptionsignal.
 18. The optical reception apparatus according to claim 17,wherein, when the plurality of reception units that comprise the firstreception unit do not receive the sub-carrier reception signal, thefirst local oscillator is turned off.
 19. The optical receptionapparatus according to claim 13, wherein: respective reception units ofthe plurality of reception units that have received the sub-carrierreception signal via a first path receive first data that has beenserial-parallel converted in parallel, and respective reception units ofthe plurality of reception units that have received the sub-carrierreception signal via a second path receive second data that has beenserial-parallel converted in parallel.
 20. The optical receptionapparatus according to claim 13, wherein the switch unit comprises: aplurality of optical branching devices that branch an optical receptionsignal that has been received; and an optical changeover switch thatselects sub-carrier reception signals to be output to the respectivereception units from optical reception signals branched off by theplurality of optical branching devices to output the sub-carrierreception signals to the respective reception units.
 21. The opticalreception apparatus according to claim 20, wherein the opticalchangeover switch comprises an optical switch that is provided tocorrespond to the respective reception units, the optical switchselecting the sub-carrier reception signals to be output to each of thereception units from the optical reception signals branched off by theplurality of optical branching devices and outputting the sub-carrierreception signals to the respective reception units.
 22. The opticalreception apparatus according to claim 13, wherein the switch unitcomprises: an optical multiplexer that multiplexes optical receptionsignals that have been received; and an optical demultiplexer thatselectively outputs the respective sub-carrier reception signalsincluded in the multiplexed optical signals output from the opticalmultiplexer to the respective reception units.
 23. An opticalcommunication apparatus comprising: a first transmission unit thattransmits a first optical transmission signal; a second transmissionunit that transmits a second optical transmission signal; an output unitthat outputs, when the first optical transmission signal and the secondoptical transmission signal share a set of information, both the firstoptical transmission signal and the second optical transmission signalto one path and outputs, when the first optical transmission signal andthe second optical transmission signal do not share the set ofinformation, the first optical transmission signal and the secondoptical transmission signal to paths different from each other; firstand second reception units that receive a sub-carrier reception signal;and a switch unit that outputs a first sub-carrier reception signal anda second sub-carrier reception signal that have been input to the firstand second reception units, wherein: when the first and secondsub-carrier reception signals share a set of information, the switchunit receives the first and second sub-carrier reception signals via onepath and outputs the first sub-carrier reception signal to the firstreception unit and the second sub-carrier reception signal to the secondreception unit, and when the first sub-carrier reception signal and thesecond sub-carrier reception signal do not share the set of information,the switch unit receives the first and second sub-carrier receptionsignals via paths different from each other and outputs the firstsub-carrier reception signal to the first reception unit and the secondsub-carrier reception signal to the second reception unit.
 24. Anoptical communication system comprising an optical transmissionapparatus and first and second optical reception apparatuses, wherein:the optical transmission apparatus comprises: a first transmission unitthat transmits a first optical transmission signal; a secondtransmission unit that transmits a second optical transmission signal;and an output unit that outputs, when the first optical transmissionsignal and the second optical transmission signal share a set ofinformation, both the first optical transmission signal and the secondoptical transmission signal to one optical reception apparatus andoutputs, when the first optical transmission signal and the secondoptical transmission signal do not share the set of information, thefirst optical transmission signal and the second optical transmissionsignal to optical reception apparatuses different from each other. 25.The optical communication system according to claim 24, wherein apredetermined parameter of a first sub-carrier used to generate thefirst optical transmission signal and a predetermined parameter of asecond sub-carrier used to generate the second optical transmissionsignal are allocated in such a way that they do not overlap each other.26. The optical communication system according to claim 25, wherein: thepredetermined parameter comprises a plurality of parameters, and thefirst sub-carrier and the second sub-carrier are arranged in such a waythat they do not overlap each other on a matrix having the plurality ofparameters as axes.
 27. The optical communication system according toclaim 25, wherein the predetermined parameter is at least one of awavelength, a polarization, and a time.
 28. The optical communicationsystem according to claim 24, wherein the first and second transmissionunits generate the first and second optical transmission signals havingwavelengths different from each other using light supplied from a lightsource.
 29. The optical communication system according to claim 28,wherein: the first transmission unit is supplied with a firstsub-carrier from a first light source; and the second transmission unitis supplied with a second sub-carrier from a second light source. 30.The optical communication system according to claim 28, furthercomprising: a single light source; and a sub-carrier generation unitthat generates first and second sub-carriers using light generated inthe single light source and supplies the first and second sub-carriersthat have been generated to the first and second transmission units,respectively.
 31. The optical communication system according to claim30, wherein the sub-carrier generation unit modulates light generated inthe single light source using orthogonal frequency division multiplexingto generate the first and second sub-carriers that are perpendicular toeach other.
 32. The optical communication system according to claim 24,wherein: when the first and second transmission units transmit data inwhich a set of information is shared, data that has been serial-parallelconverted is supplied to the first and second transmission units, thefirst and second transmission units transmit the data that has beenserial-parallel converted in parallel, and the output unit outputs boththe first and second optical transmission signals to the one opticalreception apparatus.
 33. The optical communication system according toclaim 24, wherein the output unit comprises: a switch unit that switchesoutput destinations of the first and second optical transmission signalsoutput from the first and second transmission units; and first andsecond optical multiplexers that are provided to correspond to the firstand second paths and multiplex the first and second optical transmissionsignals output from the switch unit.
 34. The optical communicationsystem according to claim 33, wherein the switch unit comprises firstand second optical switches that are provided to correspond to the firstand second transmission units and switch output destinations of thefirst and second optical transmission signals output from the first andsecond transmission units to the first optical multiplexer or the secondoptical multiplexer.
 35. The optical communication system according toclaim 24, wherein the output unit comprises: an optical multiplexer thatmultiplexes the first and second optical transmission signals outputfrom the first and second transmission units; and an opticaldemultiplexer that selectively outputs the first and second opticaltransmission signals included in the multiplexed optical signal outputfrom the optical multiplexer to the first and second optical receptionapparatuses.
 36. An optical communication system comprising: an opticaltransmission apparatus that transmits first and second opticaltransmission signals; first and second optical reception apparatusesthat receive the first and second optical transmission signals; and acontroller that controls the optical transmission apparatus, wherein theoptical transmission apparatus outputs the first optical transmissionsignal and a second optical transmission signal that shares a set ofinformation with the first optical transmission signal to the firstoptical reception apparatus according to an instruction from thecontroller and outputs a second optical transmission signal that doesnot share the set of information with the first optical transmissionsignal to the second optical reception apparatus.
 37. The opticalcommunication system according to claim 36, wherein the controller setsa communication between the optical transmission apparatus and the firstoptical reception apparatus according to at least one of a distancebetween the optical transmission apparatus and the first opticalreception apparatus, a time zone in which the communication isperformed, and a state of a transmission path between the opticaltransmission apparatus and the first optical reception apparatus. 38.The optical communication system according to claim 36, wherein thecontroller sets the communication between the optical transmissionapparatus and the first optical reception apparatus using at least oneof an allocation of a wavelength band of a sub-carrier in thecommunication between the optical transmission apparatus and the firstoptical reception apparatus, a path of an optical signal, and amodulation system.
 39. The optical communication system according toclaim 36, wherein the controller decreases a multi-value degree for eachsub-carrier and increases the number of sub-carriers as thecommunication distance between the optical transmission apparatus andthe first optical reception apparatus increases.
 40. An opticalcommunication system comprising first and second optical transmissionapparatuses and an optical reception apparatus, wherein: the opticalreception apparatus comprises: first and second reception units thatreceive a sub-carrier reception signal; and a switch unit that outputs afirst sub-carrier reception signal and a second sub-carrier receptionsignal that have been input to the first and second reception units,when the first and second sub-carrier reception signals share a set ofinformation, the switch unit receives the first and second sub-carrierreception signals from one optical transmission apparatus and outputsthe first sub-carrier reception signal to the first reception unit andthe second sub-carrier reception signal to the second reception unit,and when the first sub-carrier reception signal and the secondsub-carrier reception signal do not share the set of information, theswitch unit receives the first and second sub-carrier reception signalsfrom optical transmission apparatuses different from each other andoutputs the first sub-carrier reception signal to the first receptionunit and the second sub-carrier reception signal to the second receptionunit.
 41. The optical communication system according to claim 40,wherein: the optical reception apparatus further comprises a signalprocessing unit that processes each of a first reception signal outputfrom the first reception unit and a second reception signal output fromthe second reception unit, and the signal processing unit compensatesfor an influence of mutual interference between the first sub-carrierreception signal and the second sub-carrier reception signal.
 42. Theoptical communication system according to claim 41, wherein: the firstand second reception units respectively comprise first and second localoscillators, and the signal processing unit compensates for an influenceof mutual interference between the first sub-carrier reception signaland the second sub-carrier reception signal by controlling the first andsecond local oscillators according to the first and second sub-carrierreception signals.
 43. The optical communication system according toclaim 40, wherein: each of the reception units is configured to be ableto receive a plurality of sub-carrier reception signals, and each of thereception units makes local oscillation light generated by the localoscillator included in each of the reception units and the sub-carrierreception signals that have been input interfere with each other toselectively receive a predetermined sub-carrier reception signal fromthe plurality of sub-carrier reception signals that have been input. 44.The optical communication system according to claim 40, wherein: theplurality of reception units including the first reception unit share afirst local oscillator, the plurality of reception units including thesecond reception unit share a second local oscillator, and the first andsecond local oscillators are controlled according to the sub-carrierreception signal.
 45. The optical communication system according toclaim 44, wherein, when the plurality of reception units that comprisethe first reception unit do not receive the sub-carrier receptionsignal, the first local oscillator is turned off.
 46. The opticalcommunication system according to claim 40, wherein: respectivereception units that have received the sub-carrier reception signaltransmitted from the first optical transmission apparatus receive firstdata that has been serial-parallel converted in parallel, and respectivereception units that have received the sub-carrier reception signaltransmitted from the second optical transmission apparatus receivesecond data that has been serial-parallel converted in parallel.
 47. Theoptical communication system according to claim 40, wherein the switchunit comprises: a plurality of optical branching devices that branch anoptical reception signal that has been received; and an opticalchangeover switch that selects sub-carrier reception signals to beoutput to the respective reception units from optical reception signalsbranched off by the plurality of optical branching devices to output thesub-carrier reception signals to the respective reception units.
 48. Theoptical communication system according to claim 47, wherein the opticalchangeover switch comprises an optical switch that is provided tocorrespond to the respective reception units, the optical switchselecting the sub-carrier reception signals to be output to each of thereception units from the optical reception signals branched off by theplurality of optical branching devices and outputting the sub-carrierreception signals to the respective reception units.
 49. The opticalcommunication system according to claim 40, wherein the switch unitcomprises: an optical multiplexer that multiplexes optical receptionsignals that have been received; and an optical demultiplexer thatselectively outputs the respective sub-carrier reception signalsincluded in the multiplexed optical signals output from the opticalmultiplexer to the respective reception units.
 50. The opticalcommunication system according to claim 40, further comprising acontroller that controls the first and second optical transmissionapparatuses and the optical reception apparatus according to a state ofcommunication of the optical communication system.
 51. The opticalcommunication system according to claim 50, wherein the controller setsa communication between the first optical transmission apparatus and theoptical reception apparatus according to at least one of a distancebetween the first optical transmission apparatus and the opticalreception apparatus, a time zone in which the communication isperformed, and a state of a transmission path between the first opticaltransmission apparatus and the optical reception apparatus.
 52. Theoptical communication system according to claim 50, wherein thecontroller sets the communication between the first optical transmissionapparatus and the optical reception apparatus using at least one of anallocation of a wavelength band of a sub-carrier in the communicationbetween the first optical transmission apparatus and the opticalreception apparatus, a path of an optical signal, and a modulationsystem.
 53. The optical communication system according to claim 50,wherein the controller decreases a multi-value degree for eachsub-carrier and increases the number of sub-carriers as thecommunication distance between the first optical transmission apparatusand the optical reception apparatus increases.
 54. A controller thatcauses, in an optical communication system comprising an opticaltransmission apparatus and first and second optical receptionapparatuses, the optical transmission apparatus to output a firstoptical transmission signal and a second optical transmission signalthat share a set of information with the first optical transmissionsignal to the first optical reception apparatus and to output a secondoptical transmission signal that does not share the set of informationwith the first optical transmission signal to the second opticalreception apparatus.
 55. The controller according to claim 54,comprising: a monitor unit that monitors a state of communication of theoptical communication system; and a configuration unit that configuresthe optical transmission apparatus and the first and second opticalreception apparatuses according to a result of monitoring in the monitorunit.
 56. The controller according to claim 54, wherein the controllersets a communication between the optical transmission apparatus and thefirst optical reception apparatus according to at least one of adistance between the optical transmission apparatus and the firstoptical reception apparatus, a time zone in which the communication isperformed, and a state of a transmission path between the opticaltransmission apparatus and the first optical reception apparatus. 57.The controller according to claim 54, wherein the controller sets thecommunication between the optical transmission apparatus and the firstoptical reception apparatus using at least one of an allocation of awavelength band of a sub-carrier in the communication between theoptical transmission apparatus and the first optical receptionapparatus, a path of an optical signal, and a modulation system.
 58. Thecontroller according to claim 54, wherein the controller decreases amulti-value degree for each sub-carrier and increases the number ofsub-carriers as the communication distance between the opticaltransmission apparatus and the first optical reception apparatusincreases.
 59. A method of controlling an optical communication systemcomprising an optical transmission apparatus and first and secondoptical reception apparatuses, wherein: the optical transmissionapparatus comprises: a first transmission unit that transmits a firstoptical transmission signal; a second transmission unit that transmits asecond optical transmission signal; and an output unit that outputs,when the first optical transmission signal and the second opticaltransmission signal share a set of information, both the first opticaltransmission signal and the second optical transmission signal to oneoptical reception apparatus, and when the first optical transmissionsignal and the second optical transmission signal do not share the setof information, outputs the first optical transmission signal and thesecond optical transmission signal to optical reception apparatusesdifferent from each other, and each of the optical transmissionapparatus and the first and second optical reception apparatuses iscontrolled according to a state of communication of the opticalcommunication system.
 60. A computer-readable storage medium storing aprogram for causing a computer to control an optical communicationsystem comprising an optical transmission apparatus and first and secondoptical reception apparatuses, wherein: the optical transmissionapparatus comprises: a first transmission unit that transmits a firstoptical transmission signal; a second transmission unit that transmits asecond optical transmission signal; and an output unit that outputs,when the first optical transmission signal and the second opticaltransmission signal share a set of information, both the first opticaltransmission signal and the second optical transmission signal to oneoptical reception apparatus, and outputs, when the first opticaltransmission signal and the second optical transmission signal do notshare the set of information, the first optical transmission signal andthe second optical transmission signal to optical reception apparatusesdifferent from each other, and the program causes the computer toexecute processing for controlling each of the optical transmissionapparatus and the first and second optical reception apparatusesaccording to a state of communication of the optical communicationsystem.
 61. An optical transmission method comprising: generating afirst optical transmission signal; generating a second opticaltransmission signal; and outputting, when the first optical transmissionsignal and the second optical transmission signal share a set ofinformation, both the first optical transmission signal and the secondoptical transmission signal to one path and outputting, when the firstoptical transmission signal and the second optical transmission signaldo not share the set of information, the first optical transmissionsignal and the second optical transmission signal to paths differentfrom each other.
 62. An optical reception method that receives, whenfirst and second sub-carrier reception signals share a set ofinformation, the first and second sub-carrier reception signals via onepath and outputs the first sub-carrier reception signal to a firstreception unit and the second sub-carrier reception signal to a secondreception unit and receives, when the first sub-carrier reception signaland the second sub-carrier reception signal do not share the set ofinformation, the first and second sub-carrier reception signals viapaths different from each other, outputs the first sub-carrier receptionsignal to the first reception unit, and outputs the second sub-carrierreception signal to the second reception unit.